A recognizable and rare white wolf found wounded last month in Yellowstone National Park was shot illegally, according to results from a preliminary necropsy released this week.

"She was one of the most recognizable wolves and sought after by visitors to view and photograph," the park said in a release.

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Officials are offering a $5,000 reward for information about the shooter. A separate reward of $5,000 reward is also being offered by Wolves of the Rockies, a wolf advocacy group.

Hikers found her April 11 on the north side of the park near Gardiner, Montana. She is believed to have been shot between 1 a.m. April 10 and 2 p.m. April 11, officials said.

Park rangers euthanized her and then sent the body to the U.S. Fish and Wildlife Service Forensics Laboratory for a necropsy. Preliminary results, released Thursday, indicate she suffered from a gunshot wound after being illegally shot.

She was one of three white wolves in the park. She was 12 years old, twice the age of an average wolf at the park. She was alpha for nine years, and with her alpha male counterpart had at least 20 pups -- 14 of which lived to adulthood.