The Pinal County Sheriff's Office announced Monday that it is reopening the investigation into the April 30 shooting of Deputy Louis Puroll to settle a key unanswered question: From what distance was he shot?

The department is sending Puroll's green T-shirt, marked by a bloodstained hole, to the Arizona Department of Public Safety's crime lab. The lab will determine if the T-shirt bears evidence of gunshot residue or any other sign that Puroll was shot from a close distance, not from the approximately 25 yards he reported to investigators.

The detail is key because some outside experts have raised doubts about Puroll's story. Two medical forensic experts concluded from looking at photos of Puroll's wound that he was shot from within inches, not from many yards away.

It's "a close wound, not a distant wound, based on the appearance of the skin around the wound, which is normally what we forensic pathologists look at," said Dr. Michael Baden, a former New York City chief medical examiner currently working for the New York State Police. "We're talking inches, not yards."

Dr. Werner Spitz, former chief medical examiner for Detroit's Wayne County and author of a death-investigation textbook, said, "There's almost no doubt that this is a muzzle-contact-type injury, with the muzzle flame singeing the skin right where the bullet went by."

When asked if the bullet could have been from 25 yards away, he said, "No, it was not (even) from one yard away."

Their opinions were first reported by the Phoenix New Times in a story on the Puroll shooting published Thursday. Two other experts quoted in the story weren't as certain about the distance from which Puroll was shot.

On Friday, the Sheriff's Office put out a statement standing behind the investigation.

"After a review of all the evidence in this case, the Pinal County Sheriff's Office has closed this criminal investigation and concluded that it occurred as Deputy Puroll reported it," the statement said.

But the department changed its position Monday, saying that "to maintain the transparency of our criminal investigation, we are reopening this case."

Puroll's shooting occurred amid a raging national debate over illegal immigration, prompted by Arizona's SB 1070, which Gov. Jan Brewer had signed a week earlier. Rancher Rob Krentz was shot and killed in Cochise County about a month before Puroll was shot.

Pinal County Sheriff Paul Babeu was one of the most high-profile supporters of SB 1070, and in subsequent months he said in interviews that Mexican drug cartels control some remote parts of Pinal County like the area where Puroll was shot.

Puroll told dispatchers that day and later told investigators that he went that afternoon to watch a smuggling trail in the Vekol Valley, south of Interstate 8, near the Maricopa County-Pinal County line. He said he spotted a group of six men, five of whom were carrying large backpacks, as marijuana smugglers often do.

In cell-phone calls to dispatchers and his supervisor that afternoon, Puroll told them he was following the group from about a quarter-mile behind. Then Puroll crested a ridge, and a man about 25 yards away saw him and started firing, the deputy said. In a later interview with investigators, Puroll described it this way:

"I saw the first round go off. The muzzle flash from what I believe was the first round and I felt the impact. When I saw him, I had dropped my cell phone and GPS to the ground and grabbed my rifle that was slung in front of me and began to bring it up.

"Before I could get it up to shoot, his first round struck me in the side. I felt it. It felt like being popped with a wet towel. I knew I had been hit, and I knew that if I went down or stopped shooting there's a good chance I was going to be killed. My entire focus and attention at the point was staying on my feet and returning fire.

"I can remember telling myself, 'Use your sights; use your sights.' I centered my front sight center mass, and I squeezed a short burst on full automatic at the man that was shooting at me. He fell to the ground, his left, my right, immediately and went out of my sight. I never saw him again, and I don't believe any more gunfire came from his position, but I cannot swear to that."

Puroll said he also took some gunfire from a position perhaps 25 yards to his right but never saw those shooters and fired into the bushes in their direction, which ended the gunfire from that side.

Hundreds of police officers swarmed the area in subsequent hours, but they never found the shooters, backpacks or evidence of anyone Puroll may have shot.

Investigators did find four AK-47 ammunition magazines, one of them empty, and a cell phone connected to a 6-volt battery under a nearby tree.

The Associated Press contributed to this report. Contact reporter Tim Steller at 807-8427 or at tsteller@azstarnet.com