Colin Mulvany / AP

During the execution of a search warrant, members of the Joint Federal Haz-Mat Team, FBI and local law enforcement gather in front of the Osmun Apartments near the intersection of First Avenue and Oak Street in the Browne's Addition neighborhood of Spokane, Wash., on Saturday, May 18, 2013

SPOKANE, Wash. -- A 37-year-old man was arrested Wednesday after a pair of letters containing the deadly poison ricin were discovered in Washington state last week.

A grand jury indictment accuses Matthew Ryan Buquet of mailing a threatening communication to U.S. District Judge Fred Van Sickle at the federal courthouse on May 14.

The indictment did not say anything about ricin. However, the U.S. Postal Service said last week that two letters were discovered — one addressed to the courthouse and the other to the downtown post office — and they contained ricin in a crude form that did not immediately pose a threat to workers.

Buquet appeared in federal court in Spokane after the FBI said agents arrested him Wednesday afternoon. He pleaded not guilty.

If convicted of mailing a threatening communication, he could face up to 10 years in prison.

Ricin is a highly toxic substance made from castor beans. As little as 500 micrograms, the size of the head of a pin, can kill an adult if inhaled or ingested.

There were no reports of illness connected to the Spokane letters.

Investigators in hazardous materials suits spent most of Saturday executing a search warrant at a three-story apartment building in downtown Spokane. Witnesses reported that agents escorted a man from the building.

The Spokane investigation comes a month after letters containing ricin were addressed to President Barack Obama, a U.S. senator and a Mississippi judge. A Mississippi man was arrested in that case.

Chip Somodevilla / Getty Images file

Attorney General Eric Holder testifies before the Senate Judiciary Committee on March 6.

The Obama administration publicly acknowledged for the first time Wednesday that U.S. drone strikes have killed four American citizens since 2009, including the previously undisclosed death of a North Carolina resident who left the United States for Pakistan and was later indicted on federal terrorism charges.

Attorney General Eric Holder, in a letter to congressional leaders and chairman of key congressional committees made public on the eve of what was billed as a major counterterrorism speech by President Barack Obama, also confirmed the deaths in drone attacks in Yemen of three other Americans that already had been widely reported: those of radical cleric Anwar Al-Awlaki , his teenage son, Abd al-Rahmn Anwar al-Awlaki; and Samir Khan, the American who ran al Qaeda’s web-based propaganda magazine Inspire.  Previously the Obama administration had only acknowledged the senior Awlaki’s killing and refused to publicly confirm or deny reports of the other deaths.

The letter also confirmed that U.S. drones had killed Jude Kenan Mohammed of Raleigh, N.C., more than a  year after a local news report quoted a friend as saying he had died in an attack in Pakistan in November 2011.

Holder said in the letter that the senior Awlaki was the only U.S. citizen targeted in a drone strike.

Anonymous / AP

Anwar al-Awlaki, a U.S.-born Yemeni cleric and recruiter for al Qaeda in the Arabian Peninsula in Yemen, is shown in an October 2008 file photo.

He also provided new details about what the U.S. says were Awlaki's operational roles in terror plots, including his role in a 2010 attempt to bomb cargo planes by putting bombs in printer cartridges.

It also included an explicit explanation of the U.S. policy for targeted killings of Americans, much of which was included in a “white paper” obtained by NBC News in February.

Mohammed’s death appears to have been news to the FBI, which as of Thursday still listed him on its “most wanted” list, saying, “On July 22, 2009, a federal grand jury in North Carolina indicted Jude Kenan Mohammad for conspiracy to provide material support to terrorists and conspiracy to murder, kidnap, maim, and injure persons in a foreign country. Mohammad is at large … (and) is believed to be in Pakistan.”

A law enforcement official who spoke on condition of anonymity told NBC News: “We don’t know when he was killed. That fact was classified.”

FBI spokeswoman Shelley Lynch said in an email: "Jude Kenan Mohammed remained wanted until there was official confirmation of death.  Until now, the matter was classified and it is now appropriate for the wanted poster to be removed from our website." 

Obama is expected to discuss the drone program Thursday in a speech at the National Defense University in Washington, D.C.

Release of Holder’s letter came as classified documents obtained by NBC News raised new questions about the CIA-run drone program and whether it is consistent with public comments by Obama and other administration officials describing  the strikes as “very precise” and targeted at specific al Qaeda operatives and their associates. In fact, the documents show, the agency has frequently attacked low-level militants and foreign fighters in Pakistan whose names and nationalities were not known, as well as militant groups not directly connected to al Qaeda.

The documents, similar to those recently reported by McClatchy Newspapers, offer a window into the secretive drone program and how its actual operations sometimes differ from the public accounts provided by the administration.

They appear to officially confirm that the agency has engaged in “signature strikes” – a much discussed and controversial practice that has never been publicly acknowledged -- in which CIA drone operators target individuals based on the “signature characteristics” of suspects but whose actual identities are not clear.

They surface at a time that U.S officials appear to be scaling back the drone program – amid warnings from some  former military and intelligence officials that the attacks may be creating a backlash harmful to U.S. interests in the long run.

 When Obama was asked about the drone program last year during a Google News forum, he called it “a targeted, focused effort at people who are on a list of active terrorists.” In an April 2012 speech, then White House counter-terrorism adviser and now CIA Director John Brennan said: “The United States Government conducts targeted strikes against specific al Qaeda terrorists,” while acknowledging that drone targets included “associated forces.”

But a CIA list of 53 drone strikes in the fall of 2010 indicates that fewer than half – 22 -- listed al Qaeda operatives as the targets. Other strikes were aimed at targets that included suspected members of the militant al-Haqqani network in Pakistan, which is believed to have harbored and worked with al Qaeda; members of the Pakistani Taliban, an Islamic fundamentalist military group that aims to overthrow the Pakistani government; and members of another Pakistani terrorist network identified as the “Commander Nazir Group.”  Fourteen of the strikes listed the targets only as “other militants.”

Agency lists for other periods show a higher proportion of strikes being specifically aimed at Al Qaeda operatives. For example, during a nine month period between January and September 2011, 28 out of 42 strikes listed al Qaeda members as targets.

But in other accounts of the strikes, agency officials refer to the targeting of individuals whose identifies do not appear to be known. One 2009 attack was described as being aimed at “military aged males”  at a site “associated with al Qaeda explosives training.” Another, in 2010, described the target as “four adult males conducting weapons training.”

The CIA and White House did not respond to requests for comment about the documents. But U.S. officials have vigorously defended the drone program and their public accounts of it, while saying they are limited in what they can say because of its classified nature and the potential impacts of full public disclosure in Pakistan. As for the use of signature strikes , they have argued that “when you have a bunch of guys building explosives, you don’t need to know who they are. They are an imminent threat.”

NBC News’ Pete Williams, Chuck Todd and Tom Curry contributed to this report.

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David McDaniel / The Oklahoman file

Oklahoma's Chief Medical Examiner Eric Pfeifer, seen here looking at an X-ray on March 21, said the toll from the tornado was "horrific."

Even to a man who deals in death every day, the toll from Monday's tornado was "horrific."

That was the word Dr. Eric Pfeifer, the chief medical examiner of Oklahoma, used Wednesday to describe the challenge of identifying and performing autopsies on two dozen victims.

After working around the clock for two days, Pfeifer emerged from the morgue exhausted, his voice hoarse, but full of praise for an overburdened staff that pulled together "to get this sad job done."

This week's disaster was not the first time Pfeifer had been confronted with nature's wrath. He had been on the job for just a few days when a twister tore across the station in the spring of 2011, killing 10 people.

"I can remember him saying that he had not ever had any cases just like that," recalled Doug Stewart, a University of Oklahoma pediatrician who sits on the board that brought Pfeifer from Minnesota to run the Sooner State's once-troubled M.E.'s office, based in Oklahoma City.

This week's storm was far worse. Less than 48 hours after the funnel cloud hit, though, Pfeifer's office had determined a cause of death for every victim, identified all of them and notified their families.

Members of his board of directors said such efficiency would have been hard to come by in the years before his arrival, when a backlog of unfinished cases hit 1,500 and the office lost its national accreditation.

"We were in a crisis when we hired Dr. Pfeifer," said Chris Ferguson of the Oklahoma Funeral Board. "But he seems to me to be a crisis manager."

Before coming to Oklahoma City, Pfeifer was a medical examiner at the Mayo Clinic and a coroner for Olmsted County, Minn. He was taking over an office that was underfunded, understaffed and filled with equipment "out of the 70s," Ferguson said.

"I knew what I was getting myself into when I accepted the Chief ME position here and have focused the last two years on campaigning for resources to rebuild this once esteemed practice as well as remaining actively engaged in the practice of medicine,"  Pfeifer said in an email to NBC News.

The result, Stewart said, has been "a remarkable turnaround."

He and others said Pfeifer shook up the staff, hired an administrative chief, and cut the backlog of unfiled death certificates in half. He successfully lobbied the state for $2.5 million in funding to double the number of pathologists from three to six and update equipment.

With 22,000 cases a year, the current staff of three pathologists was pushed to the limit even before the tornado.

When a doctor in the Tulsa office left, Pfeifer personally filled in and performed his autopsies, said Charles Curtis, deputy chief of the state Bureau of Investigations. After his deputy was bounced, he worked weekends so the office wouldn't fall behind. He refused to take an offered raise until office finances were in better shape.

"He leads by example," Curtis said.

When the bodies began arriving on Monday, Pfeifer said, his office was ready.

"This team is accustomed to working 2-3 times [the number of] nationally recommended caseloads every single day of the year," he said in the email. "This small team here didn’t even need to be asked to step up effort toward this recent horrific task."

When Ferguson went to the M.E.'s office on Tuesday — the day the tornado death toll was revised downward from 51 to 24 after double-counting in the chaotic first hours — he couldn't talk to Pfeifer.

"He was in the morgue," he said. "He's hands-on."

Outside the lab, Pfeifer is a motorcycle enthusiast and a tinkerer, a welder who likes to design and build machines and who built a wood-burning brick pizza oven in his Minnesota home, colleagues said.

"He's got a whole bunch of tools and stuff but it's all in storage because he can't find time to use it," Ferguson said.

Ferguson said it was relief that Pfeifer was in charge when Oklahoma suffered its biggest disaster in years. He said the number and age of the victims would have been tough for any doctor, even a custodian of death, to face.

"He has children around the same age as some of these victims," Ferguson said. "But I think he has the ability to set those emotions aside and get the job done."

Related:

• Two years later, Joplin, Missouri remembers storm
• Heartbreaking list of tornado victims spans from babies to seniors
• Victims' bodies set to be returned to families
• Why aren't there more storm shelters in Oklahoma?
• How to help Oklahoma tornado victims

Slideshow: Tornadoes ravage Plains

Joshua Lott / AFP - Getty Images

A monster tornado hit Moore, Okla., Monday afternoon, leaving at least 24 dead.

Launch slideshow

Charlie Riedel / AP

A man salvages a guitar from a severely damaged home in Joplin, Mo., on May 23, 2011.

While Oklahoma begins to clean up after a ferocious tornado, the site of one of the worst twisters in American history — Joplin, Mo., a little more than 200 miles away — marked a solemn anniversary Wednesday.

On May 22, 2011, a tornado all but wiped Joplin off the map. The twister killed 161 people, injured more than 1,000 and wrought almost $3 billion worth of damage. It was clocked at more than 200 mph.

But the town has come back even stronger with changes to their infrastructure that are helping people stay safe. Now, nearly 80 percent of new homes include a safe room, and a new hospital will open in 2015 with windows able to withstand 250 mph winds.

“Devastation is a short walk, but determination lasts all the time,” Mayor Melodee Colbert Kean said. “Joplin is a city of hope. We know what it’s like to suffer… but know what it's like to get back up.”

Ninety percent of affected businesses are now open and 75 percent of the homes have been rebuilt.

And Mercy Hospital, once the symbol of the tornado's fury, was running again in just eight months.

A new facility will open in 2015 with walls and windows built to withstand 250 mph winds and its electrical systems securely buried under ground.

A moment of silence was held at 5:41 p.m. local time, the moment the tornado struck two years ago. Homeland Security Secretary Janet Napolitano, who earlier in the day was in Moore, Okla., to pledge federal help, attended the commemoration.

Joplin sent a support team to Moore to help with the recovery. The cities each have about 50,000 people.

The Joplin tornado damaged or destroyed 7,500 homes. On the Senate floor Wednesday, Missouri Sen. Roy Blunt said there were lessons for Moore in the rebuilding.

“For the people in Joplin, they immediately began to think about Joplin tomorrow instead of Joplin yesterday,” he said. “And two years later, it’s still a community that’s dealing with loss, but a community that’s building new schools and new businesses.”

The Federal Emergency Management Agency provided housing for 586 households after the Joplin tornado, and all but 12 have moved into longer-term or permanent homes, the city says.

NBC News' Becky Bratu contributed to this report.

This story was originally published on Wed May 22, 2013 7:22 PM EDT

A tornado warning was issued for parts of Massachusetts on Wednesday evening as a severe weather storm capable of producing a twister was spotted on radar, forecasters said.

The "dangerous storm" was located near Salem, or 11 miles northeast of Amherst, the National Weather Service warned.

Residents were told to take cover. No confirmed tornado was spotted, however, and about 45 minutes later the Weather Service changed their warning in the area to one alerting of possible severe thunderstorms with the potential for damaging winds of more than 60 mph.

The warnings were issued as the same storm front that spawned downpours and deadly tornadoes in Oklahoma marched east, forecasters said.

An area stretching from the Appalachians into the lower Great Lakes and New England was at "slight risk" of severe thunderstorms Wednesday night into Thursday.

Stronger and sometimes severe storms carrying gusty winds and hail were seen in southwestern Pennsylvania along the crest of the Appalachian range and into the Lower Great Lakes, according to the Weather Service.

The areas at risk for thunderstorms included Indianapolis, Columbus, Detroit, Boston and Cleveland but also stretched into Western New York and Connecticut. 

An earlier threat of possible isolated tornadoes farther west, in Western Ohio into the Tennessee Valley, "appears to have diminished" because of cooling from cloud cover, forecasters said.

However at least one funnel cloud was reported in central Florida in the town of Viera, according to NBC station WESH TV. 

The Northern Rockies area — from Northeast Wyoming through Western Montana — could also see storms with severe hail and wind, the Weather Service said.

Get more from weather.com

Weather.com's forecast showed a map outlining the main area of risk, which stretched from Buffalo to Charleston. It also said the main danger would be from high winds and hail, but cautioned there was a “slight risk” of tornadoes.

"Other showers and thunderstorms are possible from the remainder of the Northeast and Great Lakes into the South," it said.

"A few isolated severe thunderstorms producing damaging wind gusts and hail are possible in the lower Mississippi Valley. Showers and thunderstorms continue from the Northeast to the Southeast Thursday, although the severe threat is even lower," weather.com added.

Parts of northeast Kentucky, Ohio, southeast Michigan, western Pennsylvania and western New York were given a 3 out of 10 on Weather.com's tornado probability scale, with 10 representing the highest probability of twisters. The cities of Cincinnati, Columbus, Detroit, Pittsburgh and Buffalo were all included in this risk area.

Meanwhile, a tornado rating of 2 was given to Tennessee, most of Kentucky, much of eastern Indiana, parts of southern and eastern Michigan, eastern West Virginia, much of Pennsylvania and much of upstate New York.

Connecticut was hit by strong storms that caused some damage in northern parts of the state on Tuesday, NBCConnecticut.com reported.

A storm moved through Copake, New York, just before 5 p.m. and headed southeast through Massachusetts and along the extreme northwest corner of Connecticut, the station said. Downed trees and power lines were found in Falls Village and lightning strikes came close to homes in Cornwall.

A tree fell on cars in the high school parking lot in Falls Village. "It's just a car. We're just here to make sure all the kids were safe," said Patricia Chamberlain, superintendent, whose car was among those hit.

Thunder, lightning, high winds and hail were reported in several Conn. towns, including Salisbury, Canaan, South Windsor and Manchester.

Related:

• Full coverage of Oklahoma tornadoes
• 9-year-old, 65-year-old among first tornado victims identified
• Before and after: Tornado cuts devastating path through Oklahoma

The earth itself was at least partially to blame for why desperate schoolchildren in Moore, Okla., had nowhere to hide from Monday’s devastating tornado.

Much of the soil in Oklahoma, including Moore, is red clay -- a porous substance that makes foundations settle and basements and underground tornado shelters leak. “That’s the reason we don’t have basements,” said Tom Bennett of Tulsa, past president of the National Storm Shelter Association. In greater Oklahoma City, which includes Moore, only 3.5 percent of homes have basements, according to Reuters.

But it wasn’t just the ground under residents’ feet that was to blame. The region’s politics and economy also were factors.

“This is a red state,” said state Rep. Richard Morrissette, D-Oklahoma City, who has introduced several unsuccessful bills in the state Legislature to require so-called “safe rooms,” shelters or anti-tornado construction in homes and trailer parks. “People don’t like anything that is mandated. They don’t like it when the government says they have to do something.”

That makes Oklahoma similar to other states in Tornado Alley. “I am unaware of any jurisdiction that requires safe rooms in private homes,” said Corey Schultz, a Kansas architect who specializes in building safe rooms for schools. And only one state – Alabama – requires them in schools, he said.

Though the mayor of Moore said Wednesday he now wants the city to require shelters in private homes, Oklahoma, like other states prone to tornadoes, prefers to encourage the construction of shelters. The state has emphasized using federal funds to underwrite the optional construction of specially reinforced, above-ground “safe rooms” inside private homes rather than community tornado shelters.

But building a steel room on a concrete slab adds thousands to the price of a new home in a market where a typical property is worth $108,000. And for homeowners, spending $2,500 and up to add tornado protection to existing homes often isn’t feasible without assistance in a state where the median income is $44,000 -- $8,000 below the national figure.

That’s a tough sell, even though it could mean the difference between life and death, said Bennett, the former president of the storm shelter association.

“In-residence’ safe rooms’ are the way to go,” he said. The rooms are built to withstand EF 5 tornadoes, with winds of 250 mph – in excess of the 210 mph recorded in Moore. “But half the population can’t afford it or doesn’t have a place to put it because they live in apartments.”

FEMA, which has programs to offset the costs, estimates it costs between $6,600 and $8,700 for a steel-reinforced 8-by-8-foot room, and much more for a larger space.

In 2012, the state launched a new program to make construction of the rooms less costly. SoonerSafe pays homeowners 75 percent of the cost of building a safe room, up to $2,000. But again, the money is federal, pulled from the state’s unused FEMA funds, and winners are chosen via lottery. In 2012, 16,000 homeowners applied, and 500 “won” the reimbursements via random drawing.

“Oklahoma’s SoonerSafe Safe Room Rebate Program is a model for supporting the construction of safe rooms through the Hazard Mitigation Grant Program Grants,” said FEMA spokesman Dan Watson.

Localities can also apply for another pool of federal money, as the City of Moore was attempting to do. Moore wanted $2 million in rebates for 800 homeowners to build safe rooms, and had submitted an emergency plan to the state and FEMA as part of the application process. But according to the city’s website, changes in federal regulations created a “moving target” and delayed the program.

FEMA’s Watson said that in the past 20 years, “FEMA has invested more than $57 million in 11,768 private and public safe rooms in Oklahoma, more structures than any other state. Many were in the same area as yesterday’s tornado.”

“The State of Oklahoma has been a great partner in providing innovative mitigation solutions to residents,” he added.

Despite the construction and subsidies, Bennett estimated that less than a fifth of the state’s 4 million residents have access to meaningful private shelter from tornadoes. In Moore, according to the New York Times, only about 10 percent of homes have them.

Schultz, the Kansas architect, said Oklahoma schools are not required to have storm shelters, but can apply for federal funding to build them. Albert Ashwood, who heads the Oklahoma Department of Emergency Management, said at a press conference Tuesday that safe rooms at more than 100 schools had been funded via FEMA, but that the two schools hit in Oklahoma, Briarwood Elementary and Plaza Towers Elementary, were not among them. There are more than 1,800 public schools in Oklahoma.

“You have limited funds that are based on disasters you’ve had in the past,” he said. “When you have limited funds, you set priorities on what schools you want to ask for.”

He also said that his department was trying to determine how many schools in the state had safe rooms.

The preference for safe rooms in private residences rather than public structures is only partly about political philosophy. It’s also based on a safety calculation. Using your own shelter or a neighbor’s shelter can be faster than trying to reach a central location.

“I don’t think it’s a good idea to drive across town when there’s a tornado,” said Bennett. “That’s where community shelters fall short.”

On the City of Moore’s website, an Emergency Management notice explains that Moore has no community shelter because there is no building suitable for one, and because “overall, people face less risk by taking shelter in a reasonably well-constructed residence!”

Next door in Kansas, however, Schultz says an equally beet-red state seems to have decided to steer its disaster money to creating more public shelters. Schultz says that his state, like Oklahoma, depends on FEMA funding for tornado shelters, but has focused on adding safe rooms to schools. In 1999, tornadoes hit schools in Wichita, and though no one was killed, “that opened eyes.”

“When we send our kids to school there are two things we take for granted,” said Schultz. “One is that they’re learning something. The other is that they’ll come home safe. “

“The Enterprise tornado and now this tornado show us that’s not always the case. I truly believe in shelters in schools for that reason.”

Bennett said that he is now receiving the same kind of back-channel signals that he got after the 2007 tornado in Enterprise, Ala., where a tornado killed seven at the local high school. That led Alabama to require schools to include safe rooms or to close during tornado watches. “Oklahoma may be headed in the direction of Alabama,” he said.

On Wednesday, Moore mayor Glenn Lewis said he would propose a new ordinance requiring shelters in newly constructed single and multi-family homes. "We'll try to get it passed as soon as I can," he told CNN.

And Chris Shatswell, an Oklahoma native who now lives in Fort Worth, Texas, has created an online petition via Change.org to get storm shelters in Oklahoma schools.

So while Morrissette, the Oklahoma legislator, worries that the current attention to increasing the supply of shelters may be short-lived, Bennett is more optimistic. “This has a shelf-life. The story of the kids in Moore has an impact,” he said.

Mark Schone is an investigative editor for NBC News; Nidhi Subbaraman is a contributing technology and science writer for NBC News; Alan Boyle, NBC News Digital science editor, also contributed to this report.

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A West Point Military Academy staff member has been accused of planting hidden cameras in the shower and locker room facilities of female cadets, U.S. military and Pentagon officials told NBC News.

Sgt. 1st Class Michael McClendon has been relieved of his duties at West Point. McClendon was charged with four counts of indecent acts, dereliction of duty, cruelty and maltreatment and violations of good order and discipline. He has been transferred to Fort Drum in upstate New York.

McClendon, a decorated combat veteran of the war in Iraq, was a staff advisor responsible for the health, welfare and discipline of 125 cadets, defense officials said.

He received the Bronze Star and combat action badge during his combat tour in Iraq.

The story was first reported by the New York Times.

Separately, the Army on Tuesday said Brigadier General Bryan T. Roberts, the Commanding General of the U.S. Army Training Center and Fort Jackson, was being investigated for adultery and for being involved in a physical altercation. Roberts was suspended from his duties.

A rash of recent incidents — including an annual report showing increased sex assaults in the military, and two separate cases of men tasked with stemming sexual assault being charged with sexual assault — has critics, lawmakers, and even President Barack Obama focused on the problem.

Defense Secretary Chuck Hagel last week ordered all branches to “retrain, recredential and rescreen all sexual assault prevention and response personnel and military recruiters.”

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John Raoux / AP

An FBI investigator walks to the apartment where a man was shot by an FBI agent, on May 22, in Orlando, Fla.

Dead Boston bombing suspect Tamerlan Tsarnaev and another man — who was killed by the FBI on Wednesday — murdered three people in Massachusetts after a drug deal went wrong in 2011, law enforcement sources tell NBC News.

Sources say that what began as a drug ripoff ended in a triple homicide when Tsarnaev and friend Ibragim Todashev realized their victims would later be able to identify them.

Todashev was killed by a federal agent while giving a statement on his role on Wednesday in Orlando, Fla.

The man who was shot, Todashev, 27, allegedly attacked an agent with a knife while confessing to the 3-year-old slayings. He was not suspected of having played any role in the bombing that killed three people and injured scores more in April, but he did confess to being involved in a brutal Boston-area slaying two years ago, investigators said.

AP Photo/Orange County Corrections Department

In this May 4, 2013 police mug provided by the Orange County Corrections Department in Orlando, Fla., shows Ibragim Todashev after his arrest for aggravated battery in Orlando.

Law enforcement officials said Todashev was being questioned as part of the FBI’s effort to find and talk to anyone who had any contact with Tsarnaev, the older bombing suspect killed in a shootout with police.

The shooting occurred in the early morning hours on Wednesday, the FBI said in a statement.

“The agent, two Massachusetts State Police troopers, and other law enforcement personnel were interviewing an individual in connection with the Boston Marathon bombing investigation when a violent confrontation was initiated by the individual,” the statement said.

“During the confrontation, the individual was killed and the agent sustained non-life threatening injuries,” according to the statement.

It's not clear who shot Todashev, officials say, because -- while he was being questioned by an FBI agent -- officers from the Massachusetts state police and the Orlando police department were also present in the house where the interrogation was going on.

Todashev, they say, had spent some time in the Boston area, where he was a mixed martial arts fighter, and knew Tsarnaev there.  Investigators say he confessed to the agent in Florida that he played a role in a triple murder in 2011 in which three men were discovered slain in an apartment in Waltham, Mass. 

Brendan Mess, 25; Raphael Teken, 37; and Eric Weissman, 31, were found with their throats cut in September of 2011, and their bodies were covered with marijuana. No suspects had been arrested in that case.

A spokesperson for the Middlesex County District Attorney’s office, which is investigating the three deaths, said that the office does not discuss ongoing investigations. Relatives for the three men did not immediately return requests for comment.

Officials say FBI agents were questioning Todashev on Tuesday. He was cooperative at first, they say, but later that night, he attacked the agent with a knife, who shot and killed him. Officials say Todashev became violent as he was about to sign a written statement based on his confession.

The officials say Todashev had some connections with radical Chechen rebels, but they say it's not clear whether he had any role in radicalizing Tsarnaev.

A friend of Todashev told NBC News affiliate WESH that he was being questioned along with the man who was shot due to their connections to the mixed martial arts community in Boston.

“They were talking to us, both of us, right? And they said they need him for a little more, for a couple more hours, and I left, and they told me they’re going to bring him back. They never brought him back,” friend Khusn Taramiv, 27, told WESH.

Todashev was arrested for aggravated battery on May 4, 2013 after getting into a fight over a parking spot with another man at Premium Outlets in Orlando, according to an Orange County Sheriff’s Office arrest affidavit.

Todashev said that he pushed the other man after he “got into his face,” according to the affidavit. The man’s son then “came at him swinging,” Todashev told police. The 5’9”, 160-pound Todashev admitted to police that he was a former mixed martial arts fighter, according to the arrest affidavit.

“This skill puts his fighting ability way above that of a normal person,” the arresting officer wrote in the affidavit.

Todashev was transported to the booking and release center without incident, according to the affidavit. His Miranda warning was read but not invoked, the document says. He was released May 5 on a $3,500 surety bond, according to the Orange County Corrections Department.

The man was born in Russia and had U.S. citizenship, according to the affidavit.

A spokesman for the Orlando Police Department referred all questions regarding the shooting to the FBI.

An FBI incident review team was dispatched from Washington, D.C., and was expected to arrive in Orlando within 24 hours, FBI Special Agent Dave Couvertier said on Wednesday morning.

Todashev was also arrested in downtown Boston in 2010 following a fender bender involving his van and a car carrying two women. Todashev had to be restrained by witnesses after he aggressively confronted the women, the Suffolk County District Attorney's office told NBC affiliate WHDH. Witnesses said Todashev was clearly the aggressor, and there was physical contact between everyone involved.

However, authorities say there were no injuries and no charges were pressed.

Todashev had been in the country since 2006.

Related:

• Judge agrees to delay in case of Boston bombing suspect Dzhokar Tsarnaev
• Boston bombing survivor Marc Fucarile determined to leave hospital
• Injured marathon bombing survivors' graduation walk a 'milestone' in recovery

NBC's Andrew Rafferty contributed to this report

This story was originally published on Wed May 22, 2013 4:53 PM EDT