Young sifts through piles of files for clues that might link other slayings to the "railway killings" suspect VIDEO CNN's Charles Zewe reports on the police work still being done by the team that hunted the "Railway Killer' Windows Media 28K 80K

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From staff and wire reports

HOUSTON (CNN) -- FBI agents are looking for links between scores of unsolved slayings around the United States and suspected "Railway Killer" Angel Maturino Resendez.

So far, the 39-year-old drifter is tied to nine slayings and charged in four.

The FBI has received calls, letters and faxes from police agencies in almost every state. Five hundred files are stacked nearly a foot high at the FBI office in Houston.

"We have our work cut out for us," said FBI Agent Kimberly Wilkins, who helped negotiate the fugitive's surrender Tuesday to a Texas Ranger in El Paso.

"We're hoping to get some answers for a lot of people," Wilkins said.

FBI agent Brian Loader said that most of the cases will be eliminated because "some of the crime scenes don't match." Still, all clues are being considered, and cases are coming in as quickly as old ones can be ruled out, Loader said.

Violent crimes logged on database

The FBI maintains a database that logs and compares violent crimes by possible forensic evidence and by similar characteristics, such as the type of weapon used and the appearance of the crime scene. Experts on particular criminal types, known as profilers, help analyze the data.

FBI profiler Mark Young said the killings that police have linked to Maturino Resendez so far were all ritualistic and vicious -- the result of tremendous rage.

"I would expect we will likely see some other cases that will be attributed to the same offender," Young said.

Authorities have alleged that Maturino Resendez, a native of Mexico who went by many aliases, including Rafael Resendez- Ramirez, may have been killing for as long as 20 years.

"We've shown a person that's been virtually all over this country and in foreign countries with no residence, no real permanency any place .... just an unidentified person moving around, unnoticed," said Don Clark, who headed the FBI task force in the month-long manhunt.

Correspondent Charles Zewe and The Associated Press contributed to this report.

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