KIRKWOOD, Mo. — The former pizza shop manager who abducted two boys and held them captive tightened his psychological hold on the one he kept for four years by taking him along on the kidnapping of the second child.

By doing so, Michael Devlin convinced Shawn Hornbeck that running to the police would get both of them arrested.

Devlin essentially said, "OK, buddy, now that you're in the truck with me, you're in as much trouble as I am," said Scott Sherman, an attorney for Shawn and his family.

In the most detailed public explanation yet of how Devlin kept Shawn and the other boy under his control, Sherman and Washington County prosecutor John Rupp told The Associated Press that Shawn did all he could to stop his captor from kidnapping Ben Ownby.

They said Shawn was powerless to fight the man who had systematically abused and manipulated him for years.

Devlin told Shawn in fall 2006 that he planned to kidnap another boy, just as he had taken Shawn in 2002 while the then-11-year-old boy was riding his bike near his home in the town of Richwoods, Rupp said.

"Shawn just went ballistic on Devlin, telling him: 'There's no way another boy should have to go through what I went through,"' Rupp told The Associated Press, referring to the years during which Devlin tortured and abused the boy, keeping him isolated in an apartment while forcing him to take the name Shawn Devlin.

The details from Rupp emerged Wednesday after Devlin made his fourth and final guilty plea. In federal court, he admitted to making pornographic photographs and videotapes of Shawn and taking him across state lines to engage in sex acts.

On Monday and Tuesday, Devlin was sentenced immediately to life terms for kidnapping and abusing the boys in Washington, St. Louis and Franklin counties. Devlin received 20 consecutive life sentences, making the 41-year-old ineligible for parole until he is more than 100 years old.

The Associated Press generally does not identify suspected victims of sexual abuse, but the story of Shawn and Ben has been widely publicized, and their names are well known.

Evidence presented at the hearings painted Devlin as a calculating predator with a seemingly boundless appetite for inflicting pain on young boys — and an uncanny ability to manipulate the circuits of a child's mind.

Rupp said he didn't know of any time that Shawn ever tried to flee Devlin's captivity, because he was terrified Devlin would find him and kill him.

But Shawn's resistance to Devlin had grown so intense by late 2006 that the man realized his normal threats of murder or sexual violence wouldn't control the boy, Sherman said.

"When none of those threats can work, and Shawn was going nuts, then the only thing that was left was that Shawn had to be in as much trouble" as Devlin was, Sherman said.

Devlin's lawyers said the accounts of their client are accurate.

"I think that Shawn Hornbeck is really a hero," said Ethan Corlija. "He really threw himself on the sword many times so Ben would not have to go through any undue torture."

Devlin admitted to taking Shawn, torturing him and controlling him for four years before kidnapping Ben and keeping him for four days. A manhunt after Ben's disappearance led authorities to Devlin's apartment in suburban St. Louis on Jan. 12, where authorities were shocked to discover Shawn, as well.

It appears that Ben was in more danger than previously known.

Devlin told Shawn that he planned to kill the boy after abusing him and had no intention of taking the risk to create another "son," as he had with Shawn, Rupp said.