The death of a 100-year-old SeaTac man is being investigated as a homicide, according to the King County Sheriff’s Office.

Robert O. Benson was found dead in his home Friday, sheriff’s spokeswoman Sgt. DB Gates said. The cause of death is undetermined.

Gates says Benson’s wallet was missing from the home, where he lived alone.

The wallet is made of brown leather and is scuffed. It contained Benson’s driver’s license and credit cards from Chase, Key Bank and Discover, the Sheriff’s Office said. The wallet also contained Benson’s AARP card, proof of car insurance and  Medicare card.

The Sheriff’s Office has not said if Benson might have been killed during a burglary.

Anyone with information on the wallet or the homicide case is asked to call the Sheriff’s Office at 206-296-3311.