FORT CARSON, Colo. -- An Army sergeant convicted of unpremeditated murder in the stabbing and choking death of a fellow soldier at Fort Carson said he was by "horrified" by the crime and takes full responsibility for his actions. But he said he doesn't know why he did it.
Sgt. Vincinte Jackson was convicted and sentenced to life in prison Thursday in the death of 28-year-old Spc. Brandy Fonteneaux of Houston.
He said at the hearing he doesn't know why he killed Fonteneaux, who was found dead Jan. 8 in her room - stabbed 74 times.
"I will be forever haunted by what happened," Jackson said. " ... It's only fair that I continue to have nightmares about what I've done."
A military panel sentenced Jackson to life with the possibility of parole, though prosecutors couldn't immediately say how many years he would serve before becoming eligible.
His testimony came at the end of an emotional sentencing hearing that included statements from the families of Jackson and Fonteneaux.
The same panel of eight soldiers who convicted Jackson decided his sentence. The potential sentence for unpremeditated murder ranged from no punishment to life in prison without parole.
The panel -- the equivalent of a jury in a civilian trial -- convicted Jackson earlier Thursday after 2 1/2 hours of deliberations. It also acquitted Jackson of premeditated murder, which carries a sentence of up to life in prison without parole.
Prosecutors asked for life without parole, while Jackson's defense attorneys asked for 28 years.
Jackson's parents, seated in the gallery, linked arms as the sentence was read late Thursday. They then left without comment.
Fontenaux's mother, Verona Fonteneaux, and other members of her family said the sentence was fair.
"I think I can get my life back together," Verona Fonteneaux said. "I can tell my grandkids that they've put the bad man away."
At the end of the court-martial, Capt. Jeremy Horn, one of Jackson's lawyers, told the panel that a combination of heavy drinking and a prescription antidepressant left Jackson unable to control his own actions or form any kind of plan to commit murder.
There was some testimony that Jackson was an alcoholic. But Horn said Jackson was only an occasional drinker and that he downed three-quarters of a bottle of whiskey the night before Brandy Fonteneaux's death. He said Jackson was trying doors in a corridor and walked in Fonteneaux's barracks room because it was unlocked.
"Sgt. Jackson was on auto-pilot. ... He felt like he was watching himself," Horn said.
The prosecutor, Capt. Jason Quinn, scoffed at the defense's claim, saying Jackson made a conscious decision to leave his room and walk to Fonteneaux's, where he stood over her while she slept.
After stabbing and slashing Fonteneaux, "he decides to reach down and choke her until she is no longer in the misery that he put her in," Quinn said.
Quinn put a photo on courtroom TV screens that showed Brandy Fonteneaux after she was killed, sprawled on the floor of her room, partially unclothed with a tangled bedsheet covering part of her body.
"Sgt. Jackson wasn't negligent," Quinn said. "He intended to do what he did. He intended to kill Specialist Fonteneaux."
Jackson, an eight-year Army veteran from Rancho Cucamonga, Calif., was with the 576th Engineer Company, 4th Engineer Battalion. Fonteneaux was a food operations specialist in the 4th Engineer Battalion.
Brandy Fonteneaux knew Jackson but they were not close, according to the aunt who raised her, Bevenly Thomas. Fonteneaux had told her family that Jackson confided in her about his crumbling marriage.
Thomas said she asked Fonteneaux if she and Jackson had a romantic relationship, and she replied, "No, Mom. He's married. He's too old."
Jackson's father, Willie Jackson, broke down as he told the panel he had never known his son to be violent. He said he's still in denial about what happened.
Fontenaux's mother told the panel that she still looks at pictures of her daughter and frequently visits her Facebook page. She said the family isn't decorating for Christmas this year.
"We're still getting together as a family, but there's going to be one that's missing," Verona Fonteneaux said.