Authorities say human remains found last summer in the Umatilla National Forest of northeast Oregon are those of a 21-year-old man who vanished three decades ago.

Forest Service officials say DNA tests match Keith Zunke, who disappeared during a field trip in the forest.

The Tri-City Herald reports that Zunke was living at Stonecreek Lodge, a Walla Walla, Wash., group home for people with developmental disabilities. Stonecreek Lodge has since closed.

Zunke disappeared on Oct. 26, 1981, and was declared legally dead in 1983.

DNA tests were performed by the Oregon State medical examiner's forensic anthropologist.

Officials say a cause of death cannot be determined because the remains were incomplete.

Oregon State Police and the Umatilla County and Walla Walla County sheriff's offices also helped in the investigation.