Olathe ? A Johnson County teenager has been sentenced to life in prison for strangling his 17-year-old girlfriend in April.

The sentence handed down Friday was the only option District Judge James Franklin Davis had under Kansas law after a jury found Kevin Gunby, 19, of Roeland Park, guilty in December of premeditated first-degree murder.

Gunby continued to insist Friday that Sharp’s death was an accident.

“I truly am sorry,” he told members of Sharp’s family. “I never would have done anything to purposely hurt her.”

Defense attorney Kevin Moriarty argued at trial that Gunby choked Sharp during a “rough” sexual encounter and then panicked when he realized she was dead.

Gunby and Amanda Sharp were students at Shawnee Mission North High School. The two had dated off and on for several years, according to testimony at the trial.

They skipped class together on the morning of April 8 and went to Gunby’s house to smoke marijuana. Brad Jaynes, a teenager who was living with Gunby’s family, testified that when he came home, Gunby told him he had killed Sharp and showed him her body.

Jaynes said he helped Gunby put the body in the trunk of Gunby’s car but told police later that day.

Moriarty argued that Gunby’s actions after Sharp died were the actions of a “stupid kid” who was scared, not a killer.

But Assistant Dist. Atty. Scott Toth told jurors that based on medical testimony, it took about 10 minutes of pressure on Sharp’s neck to kill her.

Toth argued that it was impossible to strangle someone without “knowing, thinking and wanting” them to die.

The Johnson County District Court jury did not believe Gunby’s story in December, and on Friday relatives of Sharp made it clear they did not believe him either.

An uncle called Gunby a coward who refuses to say what really happened that day.

Sharp’s mother, Julie Sharp, fought through tears to describe the pain and despair she has felt since her daughter’s death. She said her grief has been compounded by the constant worry that something would happen to free Gunby.

“I already fear the day he will be released from prison,” Sharp said.

Gunby’s first chance to ask for parole will come after he serves 25 years of the sentence.

Before sentencing, Moriarty argued that Gunby should receive a new trial because of errors in the first trial, including allowing prosecutors to present testimony about a prior incident in which Gunby allegedly choked Sharp.

Davis denied the request.

Moriarty said an appeal would be filed.