HOUGHTON, Mich. (AP) — The oldest gray wolf at Isle Royale National Park has been killed — apparently by newcomers to the Lake Superior island chain, officials said Friday.

The 12-year-old male was one of two survivors that remained when officials decided to relocate wolves from the U.S. and Canadian mainland to rebuild the dwindling population.

His body was found in October. A necropsy showed it had been attacked by fellow wolves, park officials said in a statement.

The fate of the other island-born wolf, a 10-year-old female, is unknown.

“She is the final native wolf, never radio-collared, and searching for her will be a priority”î for biologists during their annual winter study at the park, said Rolf Peterson, a research professor at Michigan Technological University.