VISTA - Already bloodied by the stab wounds that ultimately would claim her life, 16-year-old Jenna Leibner began to crawl toward her mother, Robyn Leibner, who also had been stabbed repeatedly, witnesses testified Tuesday.

The two would later be found dead lying beside each other in the foyer of the family's Fallbrook home.

"He figured Jenna would want to be with her mom, so he grabbed her by the legs and dragged her to Robyn," sheriff's Detective William Altenhof testified Tuesday, recounting statements murder suspect Jason Duane Cooper made about the killings.

Cooper, 25, of Fallbrook, told the detective that In the waning moments of her life, Jenna Leibner asked to be killed, so Cooper "cut her throat," Altenhof said.

"He stated he did not want Jenna to suffer, and he wanted to stop the pain," Altenhof said.

Cooper, married to Jenna Leibner's older sister, Amber, then placed the 911 call that brought sheriff's deputies to the scene, Altenhof said. Amber Cooper has since filed for divorce.

After hearing from Altenhof and other witnesses Tuesday, Superior Court Judge Joel Pressman ruled that prosecutors have enough evidence to make Cooper stand trial in connection with slayings of the Leibners the evening of April 26, 2006.

Cooper is charged with two counts of murder with special circumstances allegations of torture and multiple murders, which could result in a death sentence or life in prison without parole. Deputy District Attorney Kimberlee Lagotta said District Attorney Bonnie Dumanis has not decided yet whether to seek the death penalty.

Cooper also is charged with attempted residential burglary in connection with an incident at the Leibner family's home almost a week before the killings. Altenhof testified that Cooper admitted trying to break into the home in a failed attempt to steal silver coins the family had.

Cooper's attorney, Wil Rumble, said Tuesday that he believes a brain injury that has caused Cooper to suffer memory loss and epileptic seizures played a role in what happened.

A U.S. Army veteran, Cooper was sent to language school in Monterey to learn Croatian a few years ago, but the Army gave him "conflicting medication" that resulted in a fall and the head injury, Rumble said. Cooper received a medical discharge from the Army and receives 40 percent monthly disability benefits from the Veterans Administration, Rumble said.

Cooper also had cuts on his body at the time of his arrest that he said were self-inflicted. Cooper told Altenhof that cutting himself was a way to relieve stress and to punish himself, and he last cut himself a week or two before the stabbings, Altenhof said.

Cooper also spoke to the detective about having a dark side that had "taken over" and that "the darkness caused him to cut himself and drew him to hurt other people," Altenhof testified.

Altenhof said Cooper seemed confused and "didn't have a whole lot of details to present" when the detective first interviewed him, but he later provided more information about what happened.

Cooper said he stabbed Jenna Leibner first, after she made a comment about him being stupid because he had difficulty reading a book by 14th-century English author Geoffrey Chaucer, Altenhof said.

A deputy medical examiner testified that Jenna Leibner suffered 56 sharp force injuries, including stabs, cuts and slashes, and that all of the knife wounds were to her face, neck, torso and arms, Lagotta said.

After that stabbing, Cooper searched the house for a gun that he said he intended to use to kill himself, and tried to clean the blood off of his hands in a guest bathroom, Altenhof said.

Cooper told Altenhof that he told Robyn Leibner what he had done when she returned to the house, and she hit him with an electronic shock collar used to train horses. He then stabbed her, Altenhof testified.

Lagotta said the deputy medical examiner testified that Robyn Leibner suffered 23 sharp force injuries.

"As he stabbed Robyn, she was saying, 'Don't,'" Altenhof said, reciting Cooper's statements to him. "He stated he stopped after she was saying 'don't' and after she stopped struggling."

Cooper told Altenhof he held onto Robyn Leibner and stabbed her as she tried to get away, Altenhof said.

After Cooper stabbed Robyn Leibner, he saw Jenna Leibner start to crawl toward her mother and dragged Jenna to her, Altenhof said.

Thomas Leibner told deputies that he arrived home around 5:30 p.m. to find Cooper kneeling over Jenna and Robyn Leibner, Deputy Wallace Henderson testified.

Thomas Leibner told Henderson that Cooper said to him, "Tom, I'm sorry I killed them. Jenna said some (expletive) to me, and I killed them."

Cooper said he ran from the house because he was scared of himself and what he might do to Thomas Leibner. Sheriff's deputies found a blood-stained knife in bushes across the street where they first saw Cooper, witnesses testified.

"He (Cooper) said that was the knife he took from the residence and the knife he was holding when he realized what had happened as he stood over the bodies," Altenhof said.

Another blood-stained knife was found in a bathroom sink in the house, Detective Jeffrey Maxin testified.

- Staff writer Teri Figueroa contributed to this report.

- Contact staff writer Scott Marshall at (760) 631-6623 or smarshall@nctimes.com.

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