The U.S. Fish and Wildlife Service has banded together with five conservation groups to offer a $15,500 reward for information about the killing of a federally protected gray wolf. The four-year-old male, known as OR-33, was found dead in late April in southwestern Oregon's Fremont-Winema National Forest, according to the agency. A necropsy confirmed that it was OR-33, which had a collar that had stopped working the previous year. The wolf died of gunshot wounds."This is a heartbreaking loss for Oregon's wolves," Amaroq Weiss, West Coast wolf advocate at the Center for Biological Diversity, said in a statement. "Wolf recovery in Oregon depends on wolves like OR-33 making their way west and thriving, so his death is a major setback." Gray wolves are listed as endangered in the western part of Oregon. "The federal offense is punishable by up to a $100,000 fine, a year in jail, or both. The maximum state penalty is a fine of $6,250 and a year in jail," according to The Associated Press.OR-33 was a lone wolf, having left the Imnaha pack in northeastern Oregon in 2015, the Fish and Wildlife Service said. Last year, "OR-33 roamed almost within Ashland city limits — a city of more than 20,000. From June 10-12, he attacked and killed two goats and one lamb at a small livestock operation northeast of Ashland," the Statesman Journal reported, citing the agency.The animal was apparently not subtle. "This wolf is acting like David Lee Roth," Greg Roberts, a media personality in Southern Oregon, told the Statesman Journal last year. "I had eight people in Ashland say that they've seen him around their property."Oregon had at least 112 wolves in 2016, according to state statistics. But the conservation groups contributing to the reward for information say that "since 2015 at least eight wolves have been poached or died under mysterious circumstances in Oregon."Quinn Read, Northwest representative of Defenders of Wildlife, said poaching in Oregon is "a huge and growing problem." She added: "We need everyone's help to catch this killer." If you have information about this case, you can call the U.S. Fish and Wildlife Service at (503) 682-6131, or Oregon State Police Tip Line at (800) 452-7888. Copyright 2017 NPR. To see more, visit http://www.npr.org/.