KIRKWOOD, Mo. – The man accused of kidnapping two Missouri boys and keeping one of them for more than four years escaped suspicion right up until the very end — largely because he had no criminal record.
In fact, Michael Devlin apparently had so little fear of being caught that he used to joke around with police at the pizza parlor where he worked, and even phoned officers when he had a dispute with a neighbor over a parking space, authorities say.
"As Claude Rains said (in 'Casablanca'), you `round up the usual suspects' and more often than not, you're right," said Charles Bahn, a professor of psychology at the John Jay College of Criminal Justice in New York. "In this case, he wasn't on the record as a usual suspect. Police did the best they could but didn't have a lead."
• Crack the case in FOXNews.com's Crime Center.
Devlin, 41, was arrested last week after police searching for a 13-year-old boy kidnapped on Jan. 8 went to Devlin's apartment in suburban Kirkwood. Police found not only the 13-year-old, but, to their utter surprise, 15-year-old Shawn Hornbeck, who vanished 4 1/2 years ago.
That Devlin escaped the scrutiny of friends, family and co-workers for so long has baffled many members of the community and led investigators to ponder whether they did enough — or relied too heavily on mistaken assumptions — in looking for Shawn.
Early in the investigation into Shawn's disappearance, authorities scrutinized area residents with records of sexual misconduct involving children. But Devlin had little more on his record than a pair of traffic tickets.
Last year, Kirkwood police even visited the apartment Devlin shared with Shawn — some neighbors assumed they were father and son — after Devlin became angry and called police to complain that a neighbor had parked in his spot. But police saw nothing to arouse their suspicions.
Also, the St. Louis Post-Dispatch reported that a co-worker of Devlin's at Imo's pizzeria tipped off police to similarities between Devlin's rusty white pickup truck and the one seen at the site of 13-year-old Ben Ownby's abduction earlier this month. But the newspaper said the tip was not given top priority because Devlin had no criminal record.
"He had the whole little town fooled," John Walsh, host of "America's Most Wanted," said in an interview. "I'd say this is a pretty smart guy."
Ultimately, the boys were rescued after two police officers who knew Devlin as occasional customers at the pizzeria noticed Devlin's pickup. Devlin turned defensive when the officers began questioning him about it.
Tom Ballman, a Kirkwood police officer and department spokesman who frequented the pizza shop, said he and others have been groping for signs they may have missed.
"Every single one of us is saying, `What could we have done differently?'" Ballman said. "How could we have gotten Shawn home earlier?"
Bahn, the criminal justice expert, said police were right to seek out known child predators because this is a crime that "not only is compulsive, it's cyclical. You not only want to solve this case, but prevent the next one from coming along."
Moreover, experts said it is not uncommon for a criminal to live peacefully and blend smoothly into the community. Some point to Dennis Rader, the Kansas man known as the BTK killer, who was a husband, father and active churchgoer even while he was on his violent spree that claimed 10 lives.
"They can appear to be just an everyday person — a good neighbor, in some cases, a family man, a conscientious employee," said Stanton Samenow, a forensic psychologist and author of "Inside the Criminal Mind."
People who commit horrendous acts "often don't have a prior criminal record," he said. "These are people who are very calculating. They are very certain that when they do what they do they'll get away with it. They're certain of their successes. They've done their homework. There's a super-optimism."
Devlin, for his part, seemed comfortable chatting with police who gathered at the pizza parlor. He also was known as a quiet, punctual worker at the funeral home where he held a night job.
Authorities also had contact with Shawn over the years; they simply failed to connect him with the boy whose face had been plastered on posters and milk cartons around town.
Shawn's friend Tony Douglas said that on three occasions, police stopped the two for being out beyond curfew. Officers gave the boys a ride home, unaware of Shawn's real identity, Tony said.
The Post-Dispatch cited another encounter between Shawn and police that occurred Sept. 29 when an officer stopped the boy, who was riding his bike about 11:20 p.m., about a mile from Devlin's apartment.
According to the police report, Shawn identified himself as Shawn Devlin and gave a birth date of July 7, 1991 — 10 days off his actual birthday. Shawn told the officer he was riding to the apartment after visiting a friend's home.
"He was wearing dark clothing and didn't have reflectors on his bike," Glendale Sgt. Bob Catlett told the newspaper. "The officer stopped him to find out who he was. He said he was Shawn Devlin, and we had no reason to doubt him."
Shawn has not spoken publicly about his ordeal. Ben talked briefly with The Associated Press on Tuesday. But like Shawn, he was asked by investigators and his parents to avoid discussing details of his captivity.
He said it was great to be back with family: "It feels like I'm getting bruises from too many hugs."
Visit FOXNews.com's Crime Center for complete coverage.