CHEYENNE, Wyo. (AP) — A 31-year-old Utah man has died in a bear attack in the Bridger-Teton National Forest in northwest Wyoming.

Officials aren’t certain yet what type of bear killed Adam Thomas Stewart of Virgin, Utah. The coroner says he assumes it was a grizzly, but he doesn’t have enough information right now to make that determination.

Fremont County Undersheriff Ryan Lee says Stewart was in a remote area checking on a research plot earlier this month.

He failed to return and he was reported missing on Sept. 7, prompting a search. His body was found last Friday between his campsite and the research plot.

Lee says Stewart was alone.

Authorities declined to release what details led them to believe it was a bear attack.