A former Wyoming state trooper was sentenced Friday to 15 years in prison for kidnapping a truck driver in what prosecutors say was an aborted murder plot.

U.S. District Judge Alan B. Johnson said he regarded Franklin Joseph Ryle's plan as half-baked. But the judge said there was no doubt his offense was serious and required a significant sentence.

Ryle, 42, pleaded guilty in July to charges he violated the civil rights of Wal-Mart trucker Richard Smidt by pulling him over and kidnapping him in January near Douglas. Ryle also admitted to carrying a firearm during the crime, a factor that added a mandatory five years to his sentence.

Ryle has said he intended to stage an accident involving the truck and his patrol car to try to get a settlement from Wal-Mart. Prosecutors have said he intended to murder the driver, but Ryle ultimately released him unharmed.

Prosecutors suggested that Ryle's plot was stymied by the truck's GPS system because Ryle realized it would have indicated the truck was parked for about an hour after he pulled it over.

The defense, however, argued that Ryle ultimately had too much empathy to kill an innocent man.

In pronouncing the sentence, Johnson said it was unclear why Ryle didn't follow through with his plan. He said it appeared Ryle was either planning to kill Smidt, or was possibly rehearsing for a later crime.

Ryle appeared in court wearing orange jail garb. Marshals removed his handcuffs, but he remained shackled at the ankles.

"There's been times when I thought about just stuffing my pistol in my mouth and just killing myself," Ryle said, his voice breaking during his statements.

Ryle apologized to the citizens of the state and the Wyoming Highway Patrol for betraying their trust.

"I don't know why I did it," Ryle said. "I don't have any idea."

Ryle had suffered from depression before his crime but he knew right from wrong, according to mental health professionals on both sides.

Prosecutor Ed Caspar of the U.S. Department of Justice urged Johnson to give Ryle a sentence of at least 19 years, the minimum level under federal sentencing guidelines. Caspar alleged that in addition to planning to kill Smidt, Ryle also planned to kill his wife, Andrea Ryle.

"This was just a coldly premeditated plan to murder two people and defraud a company for the monetary benefit of the defendant," Caspar said.

Defense lawyer James Barrett asked Johnson to impose a sentence of 12 years.

"If there's any common denominator in this case, it's exaggeration and hysteria — 'Oh, what might have been,"' Barrett said.

Barrett said Ryle's crimes couldn't be glossed over. But Barrett urged Johnson to consider Ryle's whole life, including service in the U.S. Marine Corps, 12 years with the Highway Patrol and the fact he let Smidt go unharmed.

Ryle's parents asked Johnson for leniency, saying the highway patrol had failed to get help for their son. Smidt and Kathy Abrams, Andrea Ryle's mother, asked the judge to impose the maximum sentence.

Johnson said the case was a reminder for people to get help when they need it, even when doing so might cut against the grain of the organizational culture of their workplace, such as the Marines or the highway patrol.

Barrett said Ryle could be released to a halfway house in as soon as 11 1/2 years if he receives time off for good behavior.