The eldest, adopted son of Little House On The Prairie star Michael Landon was found dead Monday, authorities said.

There was no indication of foul play when 60-year-old Mark Landon was found in a West Hollywood home at about noon, according to Deputy Lillian Peck of the Sheriff’s Headquarters Bureau.

He had appeared in three movies, most notably Us, a made-for-TV movie his father Michael Landon wrote and directed prior to his 1991 death from cancer.

Mark Landon’s cause of death is undetermined. (Photo: Getty Images)