EL PASO, Texas - Oct. 22, 2013 Update: A jury has sentenced Roger Garrett to 40 years in prison for the murder of his stepfather 37 years ago.
Oct. 21, 2013 Story: A jury has found Roger Garrett guilty of murdering his stepfather nearly 37 years ago.
Garrett, 55, could spend the rest of his life in prison.
Prosecutors say Garrett along with his mother, Lisbeth Garrett, 74, killed Fort Bliss Green Beret Maj. Chester Garrett in 1977.
The officer's body was found beaten and stabbed in the backseat of his Volkswagen Beetle which had been driven to the desert of far east El Paso County.
Assistant District Attorney Denise Butterworth told jurors Garrett should be convicted based on testimony from witnesses who each claimed the defendant confessed to the murder to them at some point in the past 36 years.
"Their stories are reasonable, they're believable, because they're the truth," Butterworth said.
The murder case had gone cold years ago and no arrests were made until February of this year.
Patrick Garrett, son of Major Chester Garrett and Lisbeth Garrett, told El Paso County Sheriff's Deputies in January that his half-brother confessed the murder to him in 1990.
Deborah Drake-Rodriguez, a then teenage love interest of the defendant, testified Roger Garrett confessed the murder to her in 1978.
Roger Garrett's ex-wife, Theresa Heffelfinger, also testified Garrett told her the same story in 1992.
Prosecutors told jurors on Monday that Lisbeth Garrett concocted the plan to kill Maj. Garrett after she learned her husband was romantically involved with another woman.
Butterworth said Maj. Garrett had been living in the bachelor officer's quarters on post.
She said when Lisbeth Garrett when to her husband's quarters she found another woman there with her clothing inside of Maj Garrett's closet.
Prosecution witnesses testified that they were told by Roger Garrett that his mother told him they would have to kill her husband because he had been physically abusive and she was frightened of being killed.
Roger Garrett took the stand on Thursday and denied the allegations from witnesses who claimed he had confessed to the murder.
"They could have preserved this Volkswagen," defense attorney Robert Morales told jurors during closing arguments on Monday. "Did we see it? Where is the evidence?"
Defense attorneys said the lack of physical evidence is more than enough for an acquittal.
They said witnesses lied during testimony and to the contrary, Roger Garrett adored his stepfather.
"The death of his father was the worst thing that ever happened to him," Morales said. "He would not, could not, and did not commit this crime."
Jurors are expected to begin deliberations Monday afternoon.
Roger Garrett is facing five years to life in prison.
Lisbeth Garrett is expected to stand trial for the murder early next year.