LIBBY, Mont. - A forensic study of blood on the .30-06 bullet that killed a 39-year-old Nevada man black bear hunting in northern Lincoln County on Sept. 16 has revealed DNA evidence that the bullet first passed through the grizzly bear before dealing a fatal wound to the hunter.

Steve Stevenson, 39, of Winnemucca, Nev., died fighting a wounded grizzly bear that hunting partner, Ty Bell, 20, also of Winnemucca, mistakenly shot thinking it was a black bear.

Initially, it was believed Stevenson died as a result of the mauling he received from the bear. In the immediate days afterward, it was revealed that Stevenson actually died as a result of the .30-06-caliber bullet fired by Bell.

Recently released tests - done at the urging of Department of the Interior - have indicated grizzly bear DNA on the bullet that killed Stevenson, revealing the bullet first passed through the bear before killing Stevenson. An autopsy recovered the bullet from Stevenson.

"It's a horribly tragic accident," Lincoln County Sheriff Roby Bowe said Thursday, releasing the information.

"It started off with a single misjudgment and ended up in a horrific act that will affect families for a very long time," Bowe said confirming the cause of Stevenson's death as a result of the gunshot wound to his upper torso.

Bowe also indicated he did not expect charges in the killing to be filed against Bell, but that decision would have to come from another agency.

"While we don't expect charges, that's not up to me," Bowe said. "We'll forward this up to (Lincoln County Attorney) Bernie Cassidy."

With the release of the latest information, which included the caliber of the rifle, Bowe said the bullet that killed Stevenson was fired from Bell's Winchester Model 70 .30-06 rifle.

"We also know Bell picked up Stevenson's gun, because his was empty, and fired more shots at the bear," Bowe said of Stevenson's Remington .30-06 rifle. Both high-caliber rifles had sighting scopes.

The two hunters were part of a four-member party that hunted the remote, rugged Purcell Mountains that straddle northeastern Idaho and northwestern Montana.

The bear was estimated to weigh 400 pounds.

The two followed a blood trail into a thick, brushy area where the bear turned on them at close quarters.

Accounts of what ensued have indicated Stevenson drew the attention of the grizzly in an attempt to attract the bear to him, away from Bell. Turning its attention to Stevenson, the large grizzly mauled Stevenson and Bell repeatedly shot at the grizzly, which some accounts put on top of Stevenson.

It was believed to be the first case that hunting season of mistaken bear identity. Subsequently, another hunter killed a grizzly near Libby, also thought to be a black bear.

In Montana, hunters must take an online exam to help them determine the difference between black and grizzly bears, tests necessary to protect the endangered species. The exam is available on the Fish, Wildlife & Parks Web site at http://fwp.mt.gov/education/hunter/bearID/

The area the men were hunting is a grizzly bear recovery zone.