With a bipartisan group of senators expected to unveil immigration-reform legislation in the next few days, there are many issues at stake. Security along the U.S.-Mexico border has been one of the most thorny issues for immigration reform.

NBC News' Mark Potter has done extensive reporting along the U.S.-Mexico border. He answered reader questions about border security earlier today. 

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Through the obstacle course of immigration, many paths to citizenship

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San Diego Police Dept.

Pedro Antonio Guzman-Gonzalez is wanted in connection with a 1990 murder.

Exactly 23 years to the day after Maria Vargas was found strangled to death inside a home in Logan Heights, San Diego, homicide detectives renewed appeals for the public’s help in finding her killer.

On March 17, 1990, San Diego Police Department officers responded to reports of a death at a home in the 2900 block of National Avenue.

When officers arrived at the scene, they discovered Vargas’ lifeless body in the bedroom of her boyfriend, Pedro Antonio Guzman.

Detectives say Vargas had been strangled to death. Guzman had fled the scene before police could question or detain him.

Since that St. Patrick’s Day murder more than two decades ago, police have been after Guzman, who’s suspected of killing Vargas.

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Detectives say it is likely Guzman, who is now 49 years old, fled to Mexico following the murder.

He is described as 5-foot to 5-foot-3, Hispanic and weighing approximately 140 pounds. He has black hair and brown eyes. Guzman was 26 at the time of Vargas' murder.

On Friday, the SDPD released a photo of Guzman in hopes of locating him and reopening the case.

Detectives are asking anyone with information on his whereabouts to contact the SDPD Homicide Unit at (619) 531-2293 or Crime Stoppers at (888) 580-8477. Up to a $1,000 reward is being offered for information that leads to the arrest of Guzman, and tipsters may remain anonymous.

Ex-LAPD officer-turned-fugitive Christopher Dorner, who went on a deadly shooting rampage and then died after a shootout and fire last week, first tried to charm fishermen in San Diego’s Driscoll Wharf into giving him a ride to Mexico, sources said.

Dorner, 33, led authorities on a massive manhunt after allegedly killing an Irvine couple and a Riverside police officer in a crime spree across Southern California that began on Feb. 3.

Dorner's deadly crimes were allegedly part of a revenge-filled plot he outlined in an online manifesto targeting law enforcement officers and their families.

Authorities searched for Dorner all over Southern California -- from Irvine to National City -- and led extensive checkpoints at the San Ysidro border, believing Dorner was trying to flee into Mexico.

Fishermen at Driscoll Wharf told NBC 7 exclusively that Dorner was on the pier near Nimitz and Harbor Island Drive on Feb. 5 trying to charm his way into a boat ride to Mexico.

“He kept saying he wanted to go fishing off Mexico. I said ‘Mexico? That’s kinda weird. You could go fishing on the bay,’” said Jeremy Smith, a local commercial fisherman.

Smith spoke exclusively with NBC 7 on Saturday night.

Smith and others at the dock said Dorner was willing to pay $200 to $400 for someone to take him out to sea. He told the fishermen he was going to be deployed to Afghanistan and just wanted to go fishing in Mexico first.

Read more from NBCSanDiego.com

But at this pier, far away from popular fishing charters, most people were making repairs on their boats, not ready to go to sea.

Smith offered to show him around a luxury yacht that was for sale docked at the pier. But he asked him to remove the military style boots Dorner was wearing to keep the white carpeting clean. Dorner declined.

"Maybe he had a gun," Smith guessed. "Usually people want to see inside."

Dorner's request for a ride surprised some local fishermen, including Roy Sherman.

“I’ve been down here for 40 years and he’s the first guy that came down here and asked for a ride,” said Sherman.

San Diego Police Lt. Andra Brown said she was not aware of this particular Dorner sighting in San Diego.

“We’re not going to discuss details of an ongoing investigation,” Brown said, and referred questions about the incident to the Irvine Police Department.

Several other law enforcement sources -- not in the San Diego Police Department -- confirmed the man described by local fishermen was likely Dorner.

Dorner did spend time in San Diego between Feb. 4 and Feb. 6.

Gift of fish tacos
A surveillance video taken behind an auto parts store in National City on Feb. 4 shows Dorner tossing bullets, a uniform and other items that linked him to the Irvine double-homicide into a dumpster.

After spending an hour at the pier the next day, the fishermen said Dorner left, but returned with fish tacos for Smith, hoping that would convince the fisherman to help him find a charter.

The witnesses reported Dorner was very friendly, always with a smile on his face, calling himself "Mike."

The man who called himself "Mike" told Smith a story about a friend who was having problems with the police and said his friend had been fired.

"I think he was talking about himself, now that I think about it," added Smith.

Dorner eventually left peacefully without his ride to Mexico, the group of fisherman said.

Driscoll Wharf is adjacent to Naval Base San Diego on North Harbor drive.

Smith said Dorner returned to the wharf on Feb. 6 but still couldn't find anyone to take him to Mexican waters.

That same day, a man fitting Dorner’s description tried to steal a boat from a San Diego marina, according to officials. An 81-year-old man on the boat was tied up but uninjured. The would-be boat thief was unable to steal the boat and fled.

Later that night, police issued Dorner's description, and the fishermen said they notified authorities of their encounter.

On Sunday, fishermen on Pier 6 at Driscoll Wharf are amazed the kind man who brought them fish tacos on Feb. 5 was the dangerous fugitive accused of fatally shooting four people, including a police officer and a sheriff’s deputy.

The 10-day manhunt for Dorner ended on Feb. 12.

After barricading himself in a Big Bear-area cabin, he died of what appeared to be a self-inflicted gunshot wound to the head, San Bernardino County Sheriff’s Department officials said. That cabin went up in flames during a shootout between Dorner and officers, and the fugitive's charred remains were later found inside.

Related:

Dorner's luck ran out, but these five accused killers continue to elude cops

Dorner died of self-inflicted gunshot wound to the head, authorities say

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McALLEN, Texas -- The sister of a federal agent wounded in an attack in Mexico said Wednesday she hoped the lawsuit filed by her brother and the family of an agent who was killed will force the government to answer their questions. 

U.S. Immigration and Customs Enforcement agents Jaime Zapata and Victor Avila were attacked on Feb. 15, 2011, in their armored sport-utility vehicle near San Luis Potosi, Mexico, shortly after picking up some equipment from another agent. Zapata died and Avila was seriously wounded. 

The lawsuit filed Tuesday in federal court in Brownsville names nearly two-dozen defendants, among them the agents' supervisors, the company that armored their vehicle and gun shops that allegedly sold two of the weapons used in the attack. It claims Zapata and Avila never should have been sent on the dangerous mission, their armored SUV was flawed and at least two of the guns used in the attack were bought in the United States and eventually smuggled to Mexico. 

"The complaint really is seeking accountability for those people to come forward and not let this happen again," said Magdalena Villalobos, Avila's sister. She said that with the two-year anniversary of the attack fast approaching, the government had failed to answer many of the families' questions. 

Zapata and Avila had driven from Mexico City to San Luis Potosi to pick up equipment from another agent from the Monterrey office. Shortly after beginning their return trip, the pair was ambushed by armed men. Zapata parked the vehicle, but when he did so the automatic door locks unlocked. Gunmen pried open the door and in their struggle to close it, the agents partially lowered the window which allowed their attackers to fire inside. 

BAE Systems, a U.S. subsidiary of the U.K.-based global defense contractor that outfitted the armored Suburban, is named in the lawsuit. The case alleges negligence in not deactivating the feature that automatically unlocks the doors. A company spokesman said he could not immediately comment, but the company has previously said the government was aware that the automatic unlocking feature had to be disengaged. 

The lawsuit names four of the agents' supervisors and alleges negligence for putting the agents in harm's way. 

The highway Zapata and Avila traveled on "was known to be patrolled and controlled by a dangerous criminal organization," the lawsuit said. Less than a month before, the U.S. government had sent a notice to all U.S. embassy employees that there was a travel restriction in place and they should not travel in the prohibited areas. 

"Despite opposition by Avila and despite having full knowledge of the dangers present with the package pick-up, Mexico supervisors instructed Avila and Zapata to proceed with the directive," according to the lawsuit. 

A diplomatic courier service offered a secure option to move the equipment rather than sending two unescorted agents to get it, the lawsuit says. 

Barbara Gonzalez, an ICE spokeswoman, said the agency doesn't comment on pending litigation as a matter of policy. 

"The U.S. Immigration and Customs Enforcement family continues to mourn the loss of Special Agent Zapata," Gonzalez said. "We honor his sacrifice and those of his brothers and sisters in the law enforcement community who have perished in the line of duty." 

Julian Zapata Espinoza, one of those allegedly involved in the attack, is awaiting trial on murder and attempted murder charges in federal court in the District of Columbia. Mexican authorities say Zapata Espinoza is a Zetas cartel member who say mistook the agents' in the Suburban for rivals. 

The lawsuit says some of the weapons used in the attack made it to Mexico even after federal investigators had opened an investigation against some of those involved in illegal weapons purchases. Several people from the Bureau of Alcohol, Tobacco, Firearms and Explosives also are named. 

Three weapons believed used in the attack have been recovered, though information has only been released on two of them, according to federal court documents. 

One was a 7.62 mm AK-47 style Draco handgun that federal authorities traced to a straw purchase by Otilio Osorio from a Texas gun shop. Osorio and his brother were sentenced to prison on weapons charges. Another was an AK-47-style semi-automatic assault rifle bought from JJ's Pawn Shop in Beaumont in another straw purchase and passed into Mexico by Manuel Barba, who has also been sentenced to prison. 

But Jim Hedrick, owner of JJ's Pawn Shop, said Wednesday that his store made a legal sale and the gun was later resold. 

"All of our paperwork was checked and all of it was legal," Hedrick said. He had not seen the lawsuit. 

Osorio, Barba and the pawn shop are among those named as defendants in the lawsuit. 

In a procedural notice to the government filed last year, the agents' lawyers sought $25 million for Zapata's family and $12.5 million for Avila. No figures were included in the lawsuit filed Tuesday.

Former Los Angeles Police Department officer Christopher Dorner -- the suspect in three killings that have targeted law enforcement and the subject of a continuing manhunt -- was suspected last week of fleeing to Mexico, according to a federal court document.

The criminal complaint filed in federal court on Feb. 7 charges Dorner with fleeing to avoid prosecution. It states that there was reason to believe he had crossed the border into Mexico.

An affidavit included in the complaint (pdf) was written by U.S. Marshals Service Inspector Craig McClusky the same day that the search for Dorner led to his burned out truck in the mountain resort of Big Bear.

McClusky recounted the Irvine Police Department's request for assistance from the U.S. Marshal Service in finding Dorner after he became a suspect in the Feb. 3 killing of Keith Lawrence and Monica Quan, who is the daughter of an LAPD official mentioned by Dorner is a manifesto that details his alleged revenge plot.

Read more from NBCLosAngeles.com

McClusky described "the recent observations of a suspect matching Dorner's description attempting to flee to Mexico," and stated "there is probable cause to believe that Dorner has moved and traveled in interstate and foreign commerce from California to Mexico" to avoid prosecution.

The document also states that U.S. Marshals were tracking a Dorner associate identified only as "J.Y.," who had been spotted in Costa Mesa, Calif., near Irvine.

The search for Dorner continued in Big Bear on Monday, even as police followed multiple reports of sightings of the former officer that turned out to be false.

Jorge Duenes / Reuters

U.S. Customs and Border Protection officers check vehicles approaching the U.S.-Mexico border in San Ysidro on Saturday.

Also on Monday, the Riverside County District Attorney's office filed a charge of murder against Dorner in the shooting death of Officer Michael Crain, who was killed in what authorities have described as an ambush.

Crain was shot Thursday while he and his 27-year-old trainee partner were sitting at a traffic light near the Riverside Freeway.

"We felt the state of the evidence dictated there was no reason to withhold filing charges," Riverside County District Attorney Paul Zellerbach said. "He's a felon at large."

The LAPD on Sunday announced a $1 million reward in the case. More than 600 tips have been received, according to the department.

Related:

Ex-cop fugitive Christopher Dorner charged with murder

Read Dorner's manifesto at NBCLosAngeles.com

Three members of a Southern California family have been missing for nearly a month after taking a trip to Mexico, loved ones say.

Roberto Muñoz, his wife Cecilia, and their grandson Armando Salinas, had gone to Mexico to visit relatives over the holidays. But just as the three were beginning their trip home, family members lost contact with them.

Relative Delphina Layton said the family had reached out to the U.S. Embassy and the FBI, to no avail.

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Cellphones belonging to the missing group appear to have been turned off, and border records show that they never crossed back into the United States, she said.

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Layton expressed frustration with the pace of the investigation.

“I need returned calls,” she said. “Somebody get back to me and tell me that you’re doing something.”

A Palm Springs, Calif., television station reported that the family had been traveling through Chihuahua, Mexico, and passing through the rough border town of Ciudad Juarez. U.S. relatives were reported to be living in the Coachella Valley, northeast of San Diego.

An undocumented immigrant accused of assuming the persona of a Texas teacher pleaded guilty Monday in a case that put a face on the growing crime of "total identity theft" in the United States.

Benita Cardona-Gonzalez, a Mexican national living in Topeka, Kan., pleaded guilty to a reduced charge of possessing fraudulent identification documents in a deal with prosecutors that calls for an 18-month prison term.

The 32-year-old was accused of completely assuming the persona of Houston elementary school teacher Candida Gutierrez.

Pat Sullivan / AP file

The victim: Houston schoolteacher Candida Gutierrez discusses the frustration of having her identity stolen. She got some satisfaction from Monday's guilty plea.

Gutierrez recounted how the thief not only opened bank and credit accounts, but assumed her entire persona — using it to get a job, a driver's license, a mortgage, food stamps and even medical care for the birth of two children. All the while, the crook claimed the real Gutierrez was the one who had stolen her identity.

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As part of the plea deal, Cardona-Gonzalez agreed not to contest deportation after serving her sentence.

Defense lawyer Matthew Works said after Monday's hearing in Wichita that his client was sorry and didn't intend to harm Gutierrez.

"She wanted to give her children a better life. That is what this is all about," Works said.

TODAY: Extreme identity thieves live as you

Gutierrez said in a phone interview Monday that she plans to attend the sentencing, which is scheduled for March 25.

"I want to see her face to face. I want to see it actually happening," Gutierrez said. "After all this time, I am still haunted. I want to be sure she is put away."

Gutierrez said she would have liked to see Cardona-Gonzalez spend a more than 18 months in prison after everything she put her through. Still, she said she was satisfied with the plea deal because she and her husband want to get the case over with and move on with their lives.

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She praised the U.S. attorney's office in Kansas and said Assistant U.S. Attorney Brent Anderson even came to Houston to talk to her about the deal. He returned her original Social Security card and birth certificate, she said.

"They were pretty amazing getting on it once we contacted them," Gutierrez said. "Brent was informative and helpful. He was very efficient."

Gutierrez first learned her identity had been hijacked when she was turned down for a mortgage nearly 12 years ago. Both women claimed they were identity theft victims and sought new Social Security numbers. The Social Security Administration turned down the request from Gutierrez, instead issuing a new number to the woman impersonating her. In another twist, Gutierrez was forced to file her federal income tax forms using a special identification number usually reserved for illegal immigrants.

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