FORT STEWART, Ga. — The only surviving witness said he can’t recall being shot and two military forensic experts testified they found little physical evidence to link a U.S. soldier to the slayings of his two Army roommates in Iraq — a crime for which the suspect could be sentenced to life in prison.

The military trial of Spc. Neftaly Platero, 34, began its second week Monday. His defense attorney called two of the Army’s own crime lab analysts to testify that they found no gunshot residue on the suspect’s hands and none of his fingerprints on the rifle and spent bullet casings fired in the killings of Pfc. Gebrah Noonan and Spc. John Carrillo Jr.

Both soldiers were found dead Sept. 23, 2010, in the room they shared with Platero, of Kingwood, Texas, at an Army base camp in Fallujah. Another roommate was shot in the head and leg but survived. Still, Spc. Jeffrey Shonk, who had a large scar behind his left ear where a bullet creased his scalp, testified only briefly Monday — saying he remembers nothing about the shootings.

Platero’s defense attorney, Guy Womack, says the evidence points to the shooter being someone other than Platero. An Army gunshot residue expert, Mayat Wyatt, testified he found none on a skin sample from the suspect’s hands and only one microscopic particle of residue on the back of his shirt.

“That is consistent in a way with a theory that he heard gunshots, walked into the room and saw the carnage, then walked out?” Womack asked the expert.

Wyatt said that’s true, but it’s also possible any gunshot residue was washed or wiped from Platero’s hands before the skin sample was taken. Evidence records show the suspect had been allowed to use the bathroom before the sample got collected.

“You’re not saying Spc. Platero did not fire a weapon, are you?” said Maj. Stefan Wolfe, the lead prosecutor.

“No, I’m not,” Wyatt replied.

Both the prosecution and defense rested their cases Monday. The military judge said jurors would hear closing arguments Tuesday morning.

The soldiers all belonged to the 3rd Battalion, 15th Infantry Regiment of the Army’s 3rd Infantry Division based at Fort Stewart in southeast Georgia. Other witnesses at the base camp testified when they first heard gunshots they suspected an attack from enemy insurgents.

“Originally, I thought we were being overrun, so I jumped on the roof to see where the breech point was,” said Maj. Craig Martin, who testified he and other security officers on the base quickly ruled out an enemy attack.

Soldiers who entered Platero’s bunk room found 26-year-old Noonan of Watertown, Conn., sprawled on the floor and 20-year-old Carrillo of Stockton, Calif., bleeding in his bed. Both had been shot multiple times in the chest.

Army fingerprint expert Shauna Steffan testified Monday she couldn’t identify any of Platero’s fingerprints on his rifle or the 18 shell casings fired from the gun. Previously, a firearms expert testified the rifle assigned to Platero fired the 18 spent shell casings found in the room. But the suspect’s attorneys say that doesn’t prove he pulled the trigger.

“I can’t tell you if he handled it or if he didn’t,” Steffan said of Platero. “When the (rifle) grips are very textured, it is very difficult to develop a print that is suitable for identification.”

No other soldiers at the base witnessed the shootings. Platero’s supervisors say he came to them hours earlier to complain about dirty conditions in their room, which he blamed on his roommates. And one soldier, Staff Sgt. Jhamaal Martin, testified last week that he heard Shonk say as he lay wounded: “Platero shot us.”

No other witnesses have said they heard those words. Col. Jonathan Leong, the Army surgeon who helped treat Shonk’s wounds at the crime scene, said it’s normal for people with head wounds to stop talking as swelling increases and their condition worsens.

Leong said Shonk’s condition rapidly declined to a point where he struggled to breathe, prompting the surgeon to cut a hole in the wounded soldier’s throat so that he could insert a breathing tube.

“I thought he was going to die,” Leong said of the wounded soldier. “He had lost a huge amount of blood from both the head wound and the leg wound.”