Moments before 18-year-old Dustin Williams of Port St. Lucie was ordered to serve 18 years behind bars for the 2006 shooting death of his best friend, Robert "Scotty" Thomas, Circuit Judge Larry Schack said he'd "agonized" over the case that began with the theft of a gun out of a sheriff's deputy's patrol car.

"There are two families who have been destroyed," Schack noted. "No parent should have to bury a child; no parent should ever have to see a child in prison."

In July, a jury convicted Williams of manslaughter and grand theft of a firearm for shooting 16-year-old Robert Scott Thomas Jr. in the forehead.

Thomas died Nov. 25, 2006, a day after Williams accidentally shot him while showing off a .380-caliber pistol Williams and some friends stole from a Martin County Sheriff's deputy's locked squad car. Court papers show the teens and a friend were in Williams' room when he pulled out the gun, removed the magazine and, not knowing a round remained in the chamber, squeezed the trigger once.

In addition to the 18 years, Schack ordered Williams to serve a concurrent term of five years for the grand theft charge.

"I recognize ,however, that I am not sentencing you for an intentional killing," Schack said. "This is one done by absolute stupidity."

Williams had faced a maximum term of 35 years behind bars, which prosecutors had requested.

Schack also rejected a plea by Williams' lawyer, Michael Kessler, to sentence him as a juvenile, or designate him as a youthful offender.

In doing so, Schack note that while free on bond, Williams in March was arrested for allegedly breaking into cars on Duval Avenue.

"Mr. Williams," Schack lectured him, "that hurt you in these proceedings — there was obviously no lesson learned."

He still faces attempted auto burglary and drug possession charges.

Earlier, Scotty Thomas' cousin, Lynsey Thomas, 62, testified the teenager's death continues to devastate their family.

"If it were up to me, I would like to see him flogged to death in public in front of a jeering crowd and then burn in hell for eternity," he said. "But obviously that's not going to happen."

Williams, he insisted, was not a victim, but a "bad apple."

"He took a pistol with a six-pound trigger pull and shot my little cousin dead between the eyes," Thomas said.

"He stood there with that gun in his hand and watched Scotty slump forward," he continued. "And he wants to act like this was some kind of accident?"

That's how Williams' father, Charles "Jay" Williams, characterized the deadly incident.

"It's been devastating for both families," he told Schack. "It's a tragic accident. ... They were best friends; you couldn't separate them."

Williams, a pale youth with glasses and short black hair, told the court his friend's death would haunt him for life.

"I never meant to hurt Scotty, he was my best friend," Williams read from a letter. "I'm asking for mercy: I never meant to harm him in any way or destroy his life, and I ask that you please not destroy mine."

After court, Thomas' mother, Denise Thomas, said her family was pleased with his punishment. She rejected Williams' statements of remorse.

"I still have never heard, 'I'm sorry,' " she said. "I have not heard that once from Dustin Williams at all since Scotty was killed."

Thomas' father, Robert Thomas Sr., agreed.

"This was his best friend that he left lying in a pool of blood, to die," he said. "I've got some buddies — and even if they weren't my buddies — I wouldn't do that to them."