The U.S. Fish and Wildlife Service is investigating the death of a wolf recently found about 45 miles southwest of Casper, a special agent said Friday.
"We have one dead wolf; we don't know what killed it," Steve Oberholtzer said from the agency's Denver office.
"We can't confirm the cause of death," Oberholtzer said. "We can't point to the probable cause of death."
The Fish and Wildlife Service, a division of the U.S. Department of Interior, has one agent working the case, and it does not comment on investigations until after they are concluded or prosecuted, he said.
Wolves are listed as an endangered species.
The intentional killing of a wolf without cause, such as witnessed predation on livestock, is punishable by up to one year imprisonment and a $100,000 fine, Oberholtzer said.
Mark Murphy of the Murphy Ranch north of the Pathfinder Reservoir said he learned from trappers that two wolves had been seen in the Horse Heaven area of the Rattlesnake Mountains on Dec. 18.
Oberholtzer confirmed the report, saying the sighting attracted a lot of attention.
Murphy said the trappers told him the dead wolf was found near Dry Creek Road between his ranch and the Dumbell Ranch, but he does not know when that happened.
Oberholtzer said a worker at a ranch, he did not know which one, found the wolf and notified the Fish and Wildlife Service's law enforcement office in Casper.
Oberholtzer said he did not know when or where the wolf was found.
The wolf wore a radio collar, but he did not know where its pack was located, he added.
In general, investigation of wolf deaths can take a long time, Oberholtzer said.
A gunshot can be easy to identify, but identifying a poisoning can weeks, if not longer, he said.
The Fish and Wildlife Service also may not release any information about a wolf death for a long time, such as a press release Monday about a wolf that had been found dead in western Colorado in April 2009, he said.
Investigators needed a month and a half to determine the cause of death of this radio-collared wolf, who had left her pack in Montana in September 2008 and traveled 3,000 miles before her death, Oberholtzer said.
Investigators determined the wolf died after ingesting the banned Compound 1080, he said. Compound 1080 is a highly toxic poison that causes agonizing deaths. In 1972, the U.S. Environmental Protection Agency banned its use, with rare exceptions.
Gray wolves, which were hunted to near extinction nearly a century ago, were reintroduced in the Yellowstone ecosystem by the Fish and Wildlife Service in 1995.
As of last week, about 348 wolves -- 247 outside Yellowstone National Park -- were in Wyoming in a total of about 45 packs, with 34 of those packs outside the park, according to a preliminary report released by the Fish and Wildlife Service.
In 2010, the Fish and Wildlife service documented 58 wolf deaths, with 40 of those killed because of livestock predation, two from natural causes, nine that were illegal or are under investigation, three unknown causes, and four others, according to the report.
Total documented predation in 2010 of sheep, cattle and other animals by wolves amounted to 65, the lowest number since 2003, according to the report.