Police will not be in a position to comment further on the circumstances of the death until after a post-mortem examination has been done, Griffiths said.
Horn has been the subject of a weeks-long search after he went missing on February 15.
Teams of Land Search and Rescue volunteers, other volunteers and police have been searching for him since.
Horn, who has dementia, walked with a limp and was non-verbal, went missing from Walmsley House, a rest home in the suburb of Richmond.
