On at least 12 occasions, U.S. immigration officials had their hands on Rafael Resendez-Ramirez and let him go, reports CBS News Correspondent Jim Stewart. Once, after being returned to Mexico, Ramirez actually did an about-face; he re-entered the U.S. and within three days is suspected of killing two women.
On Thursday, INS Commissioner Doris Meissner said she had no explanation.
"What happened in this case is something we are not entirely certain we can explain, and that is why we are investigating it," she said.
Even harder to explain is why, when Houston police had alerted the INS last year that Resendez-Ramirez was a burglary-murder suspect, the INS never entered that information into its computers.
But exactly who knew what, and when, is still fuzzy, said Deputy Attorney General Eric Holder.
"The information about the burglary-homicide was certainly passed to INS,Â" he said. Â"Who knew exactly, I'm not clear on."
What is clear is that INS officials along the Mexican border have had a file on Resendez-Ramirez since 1976, when he was first kicked out of the country. Since then he's been turned back at the border eight times and deported three times.
The most recent encounter was June 2. Records show border agents returned him to Mexico late that day. But by June 4, he is suspected of killing a Houston woman. The next day, another woman died; and on June 15, he is thought to have killed twice in Illinois.
How did he come and go so often without anyone in the Border Patrol knowing he was a suspected killer? The answer may lie in computer software. The INS's new computer system, it seems, doesn't have a place on the screen to enter that kind of information.
Added to the profile of the man of many faces and many aliases now is Resendez-RamirezÂ's own voice, reports CBS News Correspondent Bob McNamara.
The fugitive was recorded speaking to a jury in a St. Louis federal court a decade ago. He said his arrest for a forged passport was a government setup.
"They will lie to somebody,Â" he said. Â"They will promise anything to get a confession. When they hear the truth they don't believe it. They believe a lie."
Sounding like the street-savvy con artist investigators paint him, he even confessed questions about his own identity.
"I wouldnÂ't lie to you. I wouldn't try to play with your mind. But there's many things I don't know about myself. I probably couldn't tell you who I am. As far as I know, I'm just a human being and I will leave it up to you."
In the small Mexican town Resendez-Ramirez fled three weeks ago after a tip the manhunt was closing in, his common-law wife, the mother of the coupleÂ's baby girl, isn't sure who her husband really is either.
Jlietta Reyes says her husband once admitted to a murderous past, telling her: "The very first time one kills it's ugly, very ugly, but after that itÂ's not anymore."
His victims, he told her, included people at abortion clinics and gays.
While the FBI continues taking hundreds of tips about Resendez-Ramirez sightings, border-to-border searches have turned up little.
Sadly, when a Cape Girardeau, Mo. woman pounded on a neighborÂ's door late at night, she was shot to death, mistaken for the serial killer.
And 11 days after the FBI put him on its 10 Most Wanted List, a dangerous cagey drifter has left a trail of mostly shadows and smoke.