The man alleged to have sent a letter to President Obama that tested positive for the poison ricin has been charged with threatening President Obama. The Justice Department announced the charges against Paul Kevin Curtis, 45, on Thursday.

Curtis, who has worked as an Elvis impersonator, was arrested on Wednesday as a suspect in the mailing of the suspicious letters to the president and U.S. Senator Roger Wicker, a Republican from Mississippi.

Wicker told reporters Thursday that he had once hired Curtis to perform as the hip-swiveling King of rock and roll at a party.

AP

This undated photo obtained from Facebook shows Paul Kevin Curtis, 45, according to neighbors.

“I have indeed met him,” Wicker said. “He was very entertaining.”

“He was more stable then,” Wicker added.

An FBI bulletin obtained by NBC News on Wednesday indicated that both letters contained identical closing statements.

The letters, which were postmarked April 8, 2013, out of Memphis, Tenn., ended with the phrase, “to see a wrong and not expose it, is to become a silent partner to its continuance.” The letters were also signed the same: “I am KC and I approve this message.”

Curtis was arrested at his Corinth, Miss., home at 5:15 p.m. local time on Wednesday after a sweeping investigation involving federal, state, and local law enforcement. He could face a maximum of 15 years in prison and $500,000 in fines if convicted on the charges, according to the Justice Department. He is expected to appear in Oxford, Miss., district court later Thursday.

In a statement released by Curtis' brother, Jack, his family said they were "distraught to learn of the claims being made."

But, they added, "we are, however, far too familiar with Kevin's lengthy history of mental illness.  For years, our family has struggled to obtain medical assistance for Kevin, who has been diagnosed as bipolar."

They said they they were able to get Kevin to take medication three years ago, but he recently stopped.

"Sadly, we have been informed there is no legal way for us to force him to follow his doctors' instructions," the statement read. "When Kevin is taking his medication as prescribed, he is a loving, compassionate person."

The suspicious letter addressed to President Obama was flagged at an off-site White House mail-processing facility.

Sheriff Jim Johnson of Lee County, Miss., said that a third letter received by a Mississippi judge on April 10 included “wording that was of interest” as well as some “suspicious content.” The typewritten letter with no return address was postmarked from Memphis.

Two federal officials said late on Wednesday that initial laboratory tests on the material in the letters had shown some levels of ricin, but that the results were inconclusive.

On Thursday the FBI said that further laboratory testing confirmed the presence of ricin in the letters. Further forensic exams were being conducted.

In a statement released Wednesday, Wicker thanked authorities for their efforts.

“Gayle and I want to thank the men and women of the FBI and U.S. Capital Police for their professionalism and decisive action in keeping our family and staff safe from harm,” the statement said.

A dangerous substance made from castor beans, ricin can kill in 36 hours, and does not have an antidote. An FBI official told NBC News that the agency did not initially believe the letters bore any connection to the Boston Marathon bombings on Monday, which killed three people and injured more than 176.

Please check back for more on this breaking news story.

NBC News’ Kristen Welker and Erin McClam contributed to this report.

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A Maryland high school student has been committed for psychiatric evaluation after his peers raised concerns about him, prompting investigators to search his locker and hospitalize him after finding a "credible threat," an official said.

Investigators and school security found graphs, charts, diagrams, and lists in the Laurel High School student's locker on Monday that suggested he may be planning to harm other people, said Pete Piringer, spokesman for the city of Laurel.

"There were no weapons involved, although investigators believe the student did have access to weapons," Piringer said. "Along with that potential access and the items they found in his locker, his behavior, and the fact that the classmates were uncomfortable, all led to it being a fairly credible threat."

The student -- whose identity and age were kept private -- was taken to a local hospital for an emergency committal, where he still remains. He was never charged or arrested, Piringer said.

"The student was not at the school at the time [of his hospitalization]. His family was cooperating," Piringer said.  "He's getting some psychiatric evaluation."

The school never faced any direct threats, and Laurel High's school day proceeded as normal, he said. Piringer credits the student's concerned classmates -- who brought their worries to a teacher last week -- with potentially averting a threat.

"The teacher concurred with their assessment and advised security, security then called us on Monday," Piringer said. "A large part of the credit needs to be given to the students in the first place for coming forward and notifying the authorities. Fortunately, the student is now, with the cooperation of his parents of course, at the hospital getting some medical attention."

Laurel, Md., is about 20 miles southwest of Baltimore. Laurel High School Principal Dwayne Jones wrote on the school's website after Monday's incident, "At no time were any students threatened, harmed or placed in danger. It is my belief that the cooperation between Laurel High School and the Laurel City Police is a prime example of how schools and local law enforcement can work together to insure the well-being of students."

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Lake County Sheriff'S Department / AP

Von. I. Meyer, 60, of Cedar Lake, Ind., seen in an undated photo provided by the Lake County Sheriff's Department, allegedly made threats to shoot people at the school where his wife worked during an argument.

A man was arrested after allegedly threatening to "kill as many people as he could" at a school during a heated argument with his wife, police in Indiana said Sunday.

Interim Cedar Lake Police Chief Jerry Smith said he believed Von I. Meyer, 60, was just bluffing when he made the ominous remark early Friday, NBCChicago.com reported.

Meyer, who was arrested Saturday on seven felony charges, initially threatened to set his wife on fire, then said he would kill her "at the school" where she worked and "would kill as many people as he could before police could stop him police," Smith said.

Meyer's wife works at the cafeteria at Jane Ball Elementary School, less than 1,000 feet from the couple's home in Cedar Lake, about 45 miles southeast of Chicago.

Smith said Meyer's wife stayed away from that school Friday and police boosted security at the elementary school and three other area schools as a precaution, taking those steps before 26 people, including 20 students, were shot and killed at an elementary school in Newtown, Conn.

"We just didn't want to take any chances," he said of the extra security at the schools.

47 guns hidden in house
Although police found 47 guns and ammunition hidden throughout Meyer's two-story home after they arrested him, Smith said most of those weapons were antique collector guns and he believes Meyer was not serious about his school threat.

He said Meyer's wife told officers their relationship was turbulent and he had often threatened her.

"If people followed through on all the threats they've ever made — things said in anger that they don't really mean and regret — our population in this country would be half of what it is," he said. "This was something he said in the heat of an argument. He hadn't been plotting this."

Meyer fled his home early Friday after his wife reported the alleged threats to police, and he may have gone into hiding in a densely wooded area around his home, Smith said.

Police watched the house, but Meyer apparently slipped back into his home at some point. He was arrested there without incident Saturday on felony intimidation, resisting law enforcement and domestic battery charges.

Meyer remained jailed Sunday without bond at the Lake County Jail, pending an initial hearing on the charges. It wasn't clear Sunday whether he had an attorney yet.

Police initially said Meyer was "a known member of the Invaders Motorcycle Gang," but Smith said Sunday evening Meyer is not an active member of that group, although he was affiliated with it in his youth.

Smith said security would remain high at the area's school in the coming days, mostly because of the heightened concerns nationwide in the wake of the deadly shooting rampage in Connecticut.

"One of your greatest fears is that someone might try to be a copycat," he said.

Hoax threat in Conn., Texas rumors
Separately, police in Bristol, Conn., took a person into custody Sunday night after a false online threat was made against a school there, NBCConnecticut.com reported.

According to police, a juvenile made threats against Bristol Central High School – about 25 miles away from the scene of Friday’s elementary school massacre.

Upon further investigation, the threat was found to be a hoax.

Meanwhile, extra police will be on duty at a school campus in Texas Monday morning after rumors of an alleged security threat there started spreading over the weekend, NBCDFW.com reported.

Leaders at Granbury High School, south-west of Forth Worth, issued a statement to concerned parents stating the district is actively investigating the threat and the threat rumor has not been confirmed.

NBCChicago.com’s Rick Callahan, NBCDFW.com and NBCConnecticut.com contributed to this report. 

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Traffic stands still near LSU's campus Sept. 17, 2012.

Students, professors and staff at Louisiana State University were allowed to return to the school’s main campus in Baton Rouge Monday night, hours after a bomb threat forced a full-scale evacuation, school officials said.

“All classes and events scheduled for Tuesday, Sept. 18 will be held as planned, and university employees and students should plan to return to their normal schedules on Tuesday,” LSU’s website said Monday night.

LSU Police and other law enforcement agencies are still investigating the origin of the threatening call.

Law enforcement officials had been on high alert since a call came in at 11:32 ET saying there was a bomb on the university’s grounds, university spokeswoman Christine Calongne said.

View the latest developments on breakingnews.com

Students and staff were sent text messages and an alert was posted on the campus website warning, "A bomb threat has been reported on the LSU campus. Please evacuate as calmly and quickly as possible."

Classes and a news conference with LSU football coach Les Miles were canceled Monday due to the threat, officials said. Students and staff were asked to stay off campus as the university investigated the bomb threat.

"It is important for all members of the LSU community -- faculty, staff and students -- to remain off campus unless specifically instructed to return," the university said on its website.

Capt. Doug Cain of the Louisiana State Police told The Associated Press that state police bomb technicians were on the scene. Cain said police were talking to their counterparts in both Texas and North Dakota where university bomb threats were reported last week.

Traffic was at a standstill as the main campus’s 30,000 students, professors and staff evacuated school grounds. Buses loaded with students barely moved from the central part of LSU’s campus, according to The Advocate in Baton Rouge.

Andrew Arceneaux, an LSU student studying business administration, joined other students and waited for buses to arrive so they could leave campus.

“I was in the middle of taking a test and they walked in and told us we had to leave campus,” Arceneaux told the Advocate.

Both the University of Texas in Austin and North Dakota State in Fargo received threats on Friday. The threats prompted the evacuation of both campuses. No explosives were found at either university.

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