UPDATE: Homicide Squad detectives have charged a 31-year-old man with one count of murder. He is due to appear in Mandurah Magistrates Court on Tuesday, July 14.
The two men are known to each other.
PREVIOUSLY: A man in his 70s is believed to have been murdered in his Mandurah home on Sunday evening.
Police were called to the Mandurah Terrace unit at about 9.45pm and found the man dead.
A person known to the deceased man is currently assisting police with their inquiries.
Homicide Squad detectives, with the assistance of Mandurah Detectives, are investigating the death.
Anyone with any information regarding this incident is asked to call Crime Stoppers on 1800 333 000, or report online at www.crimestoppers.com.au.