STEPHENVILLE, Texas — A ballistics expert testified Tuesday that “American Sniper” Chris Kyle, a former Navy SEAL considered the deadliest sniper in U.S. history, was shot with his back turned and his gun holstered.

Fellow veteran Eddie Ray Routh is charged with two counts of murder and one count of capital murder in connection with the fatal shootings of Kyle, 38, and friend Chad Littlefield, 35, during the trio’s trip to an outdoor shooting range near here on Feb. 2, 2013.

Routh, 27, a former Marine, is facing a possible life sentence if convicted and has pleaded not guilty by reason of insanity.

On Monday, as the nine-day trial wound down in this mostly-rural county about 100 miles southwest of Dallas, one of the final state witnesses testified that the two victims were both found with their guns holstered, the safeties on.

“They were never unholstered,” New Jersey-based forensic expert Howard J. Ryan told the lead prosecutor.

Based on evidence gathered at the crime scene, including bloodstains and gunpowder residue, Ryan said two scenarios were possible: Kyle was shot and immediately fell, or was shot again as he lay on the ground.

Either way, Ryan said, Kyle was shot in the back, including two fatal shots, one of which struck his spinal cord.

Kyle was shot five times in the back and side and once in the side of his head, prosecutors have said. Littlefield was shot seven times.

Given Kyle’s experience that included four tours in Iraq, Ryan said, “If he’s faced with a confrontation, I have to believe he’s going to engage. He never saw it coming.”

“Either way, he never saw it coming?” Erath County District Attorney Alan Nash asked.

“Never saw it coming,” Ryan said, calling the shots “incapacitating.”

Nash showed a crime scene photograph of the victim’s bloodied bodies, and Ryan — who has visited the scene — marked where he believed the shooter stood, on a shooting platform between the bodies.

“I don’t think it’s coincidental that the position of the shooter was in an area where he could engage two targets either simultaneously or in rapid succession,” Ryan said, noting that before the shooting, “there was some shooting going on down range” with a revolver used by the victims and later recovered at the scene, empty.

“I don’t think it’s coincidental that he waited until that revolver was empty” to shoot, Ryan said of the accused.

The expert said all of the shots were fired at the victims from less than 10 feet away, rapid-fire.

“When gunfire erupts, people move,” Ryan said. “The only times you don’t see that is when something happens quickly and very decisively.”

Prosecutors have called more than two dozen witnesses to bolster their argument that Routh was long-troubled. After he was honorably discharged in 2010, they noted that he smoked marijuana, drank heavily, threatened to shoot himself and others, exaggerated his military service and tried to use PTSD as an excuse when arrested for drunken driving. On the day of the shooting, they noted Routh drank, smoked marijuana and threatened his girlfriend with a knife.

Their first witness, Kyle’s widow, testified tearfully about her memories of that day and her husband’s efforts to help fellow veterans suffering from PTSD, clutching his dog tags on the stand. Taya Kyle remained in court afterward, crying quietly, as prosecutors displayed graphic crime scene photographs of her husband’s body.

Kyle, 40, returned to the gallery Tuesday with other relatives to watch prosecutors display the same graphic pictures, days after she had traveled to Los Angeles for the Oscars, where she wore a green strapless gown on the red carpet and again carried her late husband’s dog tags. The film based on her husband, “American Sniper,” was nominated for best picture.

Routh declined to testify. The defense called more than a half dozen witnesses, including a forensic psychiatrist and relatives who testified that before the shootings Routh suffered from mental illness when he returned from serving in Iraq and Haiti.

After the shootings, Routh drove Kyle’s truck to see his sister and brother-in-law, who then contacted 911 and told a dispatcher in a call played for jurors that Routh had confessed to shooting the men and appeared “psychotic.”

Closing statements could start as soon as Tuesday.

The jury of 10 women and two men has not been sequestered, despite the national attention the case has drawn, but the judge has said he intends to sequester the jurors once deliberations begin.

It’s not clear if any of the jurors are veterans. During jury selection, they completed a questionnaire that asked whether they or their relatives had served in the military, but the county clerk has declined to release their responses.