Mexican drifter Rafael Resendez-Ramirez is at the top of the FBI's "Most Wanted" list, having been linked to at least eight murders around the U.S.
And, police in the Mexican state of Chihuahua are working with the FBI and a Canadian criminologist to investigate Resendez-Ramirez in connection with 187 unsolved killings in Juarez, Mexico.
The Canadian investigator, Candace Skrapec, has been working with the police in Juarez for the past month.
There have been two new sightings of a man fitting the FBI's description of the suspect.
Two motorists say they think they saw a man who looked like the accused railroad serial killer in New Mexico Monday. Resendez-Ramirez may have been walking alongside a railroad near Mountainair.
But because he has used more than 30 aliases, the FBI says Rafael Resendez-Ramirez's name isn't as important as his picture.
The suspect has been charged with two slayings in June in Illinois. He also is wanted for questioning in five Texas killings and a 1997 homicide in Kentucky.
The suspect's real name is Angel Leoncio Reyes Recendis, according to a birth certificate. The 39-year-old was born in Izucar de Matamoros, Puebla, Mexico, officials say.
Because most of the public knows the wanted man as Resendez-Ramirez, the FBI will continue to use that name.
"We've got a lot of fliers out there all over the place with Rafael Resendez-Ramirez on them," FBI special agent Don K. Clark told the Associated Press. "I don't want to confuse the public. The public has given us some very good information with the name that's known. We want to stick with that."
Despite his many names and alleged crimes, his mother, wife, and other family members say they can't believe he's wanted for murder.
His wife, Julieta Dominguez Reyes told The Houston Chronicle that he is a model husband, and that the couple recently bought a house with their infant daughter near the Texas border. She said her husband never showed signs of being violent.
And the uncle whose name has been borrowed says the man being sought "never gave any sign of being a criminal."
While U.S. officials say the suspect is a user of drugs and alcohol, and is believed to be armed, no one in the town of Rodeo, Mexico, where he lived with his family, recalls seeing Angel in any cantina. He has no police record and has never been seen with any weapon.
Although he has been detained by immigration authorities almost a dozen times, he always was released. Illegal aliens' names and fingerprints go into a national computer system that identifies fugitives, but in this case the system didn't.