Graham and defense attorney Dan Cogdell in court for the verdict

NEW BRAUNFELS, Texas (CNN) -- Former Air Force Academy cadet David Graham was found guilty of capital murder Friday for allegedly conspiring with his one-time girlfriend to kill another teen-age girl to atone for a sexual fling.

Graham, 20, sighed slightly and swallowed hard as District Judge Don Leonard sentenced him to life in prison. His only comment was a curt "Yes, sir," when Leonard asked him if he understood his right to appeal.

After the sentence was passed, the father, mother and two brothers of the 16-year-old victim, Adrianne Jones, were allowed to address Graham and thank the jurors, who delivered the guilty verdict after deliberating for about 10 hours over two days. They had the option of convicting Graham on a lesser charge of murder or aggravated kidnapping.

"David, every evening I remember my daughter. And all I can think about was her fear, her tears and her realization that you betrayed her trust," said Linda Sue Jones. "I hope that everyone remembers our daughter with the integrity that she has, because she's still among us.

"I remember her eyes with joy -- you will [remember] with fear," she said addressing Graham.

Glowering at Graham, the victim's brother, Justin Jones, said, "I have no hate for you. I can't hate an animal, for they're ignorant, dumb and blind."

Murder the result of jealousy

Jones' body was found in December 1995 near a lake in Grand Prairie, a city near Fort Worth. The trial was moved to New Braunfels, near San Antonio, because of pretrial publicity.

From left, the victim's father, mother and brother Scott address Graham after the verdict is read

Prosecutors say Graham lured Jones into a car in which his then-girlfriend, Diane Zamora, was waiting. The duo drove to a remote area, the attorneys say, where Zamora hit Jones over the head and Graham then shot her.

Prosecutors contend that the murder was Graham's way of proving his love for Zamora, after telling her that he had had sex with Jones after a high school track meet.

Trial witnesses described the relationship between Graham and Zamora -- which began in August 1995 when both were high school seniors -- as obsessive and all-consuming. After high school, when he went off to the Air Force Academy in Colorado and she went to the Naval Academy in Maryland, they wrote each other letters every day.

Roommate broke the case

The slaying went unsolved until the summer of 1996 when Zamora confessed to a roommate, who alerted authorities. When Graham was questioned, he confessed.

"I just pointed and shot," Graham wrote in a statement given to police. "When this precious relationship that we had was damaged by my thoughtless actions, the only thing that could satisfy her womanly vengeance was the life of the one that had, for an instant, taken her place."

However, during the trial, Graham's defense team contended that Zamora acted alone in killing Jones and that Graham had confessed in a misguided attempt to protect her. They also attacked the quality of the police investigation.

Despite the defense lawyers' assertion that Graham was not present when Jones was killed, they never offered an alibi for their client.

Zamora was convicted of capital murder in February and sentenced to life in prison. She is appealing that conviction and refused to testify at Graham's trial, invoking her Fifth Amendment right against self-incrimination.

At the request of the Jones family, prosecutors did not seek the death penalty against either Graham or Zamora.

"The Cadet Murder Case" by A. W. Gray "Blind Love: The True Story of the Texas Cadet Murders, Vol. 1" by Peter Meyer "Double Jeopardy: Obsession, Murder & Justice Denied" by Bob Hill "O. J. Unmasked: The Trial, the Truth, & the Media" by M. L. Rantala "Power to Harm: Mind, Medicine, and Murder on Trial" by John Cornwell Click here for additional reading on Murder Trial