The blood of two males and two females was discovered on Staff Sgt. Robert Bales' pants, shirt, gloves, rifle and other items, said Christine Trapolsi, an examiner at the Army's Criminal Investigation Laboratory.
To preserve the rest of the evidence, she said she only tested a portion of the bloodstains, and it's possible more DNA profiles could be discovered with additional testing.
Trapolsi testified Thursday at a preliminary hearing in Bales' case. The hearing, at Joint Base Lewis-McChord south of Seattle, will help determine whether the case advances to a court martial. Afghan villagers and soldiers are expected to testify by video from Afghanistan Friday, Saturday and Sunday nights.
Bales, a 39-year-old Ohio native and father of two from Lake Tapps, Wash., could face the death penalty if ultimately convicted of 16 counts of premeditated murder and six counts of attempted murder in the March 11 attack in southern Afghanistan.
Prosecutors say that Bales dressed in a T-shirt, cape and night vision goggles, without any body armor, and slipped away from his remote post, Camp Belambay. He first attacked one village, returned to the base, and headed out again to attack another village, they say.
In between, he woke a fellow soldier, reported what he'd done, and said he was headed out to kill more, the soldier testified. But the soldier didn't believe what Bales was saying, and went back to sleep.
Nine children were among the victims, and 11 of the victims were from the same family.
Another forensic expert from the Criminal Investigation Lab, fiber specialist Larry Peterson, testified Thursday that a small piece of fabric that matched the cape Bales was reportedly wearing was discovered on a pillow in one of the attacked compounds. Prosecutors referred to the cape as a blanket, but Peterson said it was more like a decorative covering for a window or doorway.
Bales has not entered a plea and is not expected to testify. His attorneys, who did not give an opening statement, have not discussed the evidence, but say Bales has post-traumatic stress disorder and suffered a concussive head injury during a prior deployment to Iraq.
A U.S. agent who investigated the massacre testified Wednesday that local villagers were so angered it was weeks before American forces could visit the crime scenes less than a mile from a remote base.
By that time, bodies had been buried and some blood stains had been scraped from the walls, Special Agent Matthew Hoffman of the Army's Criminal Investigation Command testified Wednesday.
Other stains remained, on walls and floors. Investigators also recovered shell casings consistent with the weapons Staff Sgt. Robert Bales reportedly carried.
He also said Bales tested positive for steroids three days after the killings.
Bales leaned back in his chair at the defense table and betrayed no reaction as an Army doctor, Maj. Travis Hawks, gave clinical descriptions of treating the wounded villagers as they arrived at a nearby forward operating base.
One young girl had a large bullet wound in the top of her head, he said. She was unresponsive at first, but survived after treatment.
A woman had wounds to her chest and genitals, but she and her relatives insisted that the male doctors not treat her. Prosecutors displayed photos of the victims being treated.