A man charged in a bank robbery and murder 13 years ago was captured with the help of a tipster and DNA secretly collected from an envelope when he coincidentally filed a fraud complaint, authorities said.

Richard Leon Wilbern, 56, was arrested Tuesday when he went to meet with FBI agents in Rochester, New York, for what he thought was a meeting about his complaint.

Wilbern had been on the FBI's radar since March, when a former co-worker named him as a suspect in the August 2003 robbery of a credit union on the Xerox Corp.'s Webster campus where he once worked.

Bank customer Raymond Batzel, then 51, was fatally shot in the head and another customer was wounded when a man wearing an FBI jacket, dark glasses and a U.S. Marshal's badge opened fire after telling an employee he was there for a security assessment. The robber escaped with more than $10,000.

The co-worker's tip followed a March news conference during which FBI agents released photos of the suspect and offered a $50,000 reward for help in solving what had become a cold case.

"We were given Richard Wilbern's name and hard facts and details about his history," Adam Cohen, special agent in charge of the FBI's Buffalo office, said at a news conference in Rochester.   

In what Cohen called "an incredible coincidence," investigators were looking into the tip when Wilbern called the FBI to report a suspected real estate scam, court documents show.   

Agents met with Wilbern in July to discuss his complaint. During the second meeting, they had him sign paperwork and lick an envelope from which they obtained a DNA sample, they said.

They matched that sample to one taken from an umbrella left behind at the bank robbery 13 years earlier, U.S. Attorney William Hochul said.

Wilbern was charged Tuesday with bank robbery resulting in death and weapons counts. During an initial appearance in federal court, he requested a public defender. A detention hearing was scheduled for Oct. 19.

Wilbern, who served prison time for a 1980 bank robbery, worked at Xerox from 1997 until being fired in 2001. He had sued the copier company for racial discrimination in 2000, a complaint dismissed by a judge in December 2002 -- eight months before the deadly bank robbery.

Wilbern also admitted in 1986 to possession of a sawed-off shotgun in Richmond, Va., and spent two years in a Virginia state prison, according to the Democrat & Chronicle newspaper. He was also was arrested in Ohio for possession of stolen property in 2004, the newspaper reported.

Xerox spokesman told the paper that the company did not do criminal background checks in 1997 and was unaware of Wilbern's criminal history.

In the 2003 robbery, Wilbern walked into the credit union on the company's Webster campus and identified himself as an FBI agent.

After questioning employees about their security arrangements, he pulled two handguns from under his jacket and announced a robbery.

Batzel was shot in the head after getting into a "brief verbal altercation" with the assailant, according to the complaint against Wilbern that was obtained by the Democrat & Chronicle. Joseph Doud, then 28, was shot in the shoulder but survived.

If convicted in the Xerox Federal Credit Union robbery and murder of Batzel, Wilbern could face the federal death penalty. Wilbern is scheduled to appear in court for a detention hearing Oct. 19.

"It was my prayer that I would live long enough to see this case come to justice," Batzel's 89-year-old mother said at Wednesday's news conference, "and I'm sure that's what's going to happen now."

The Associated Press contributed to this report.