Elderly man charged over his wife's stabbing death

An elderly dementia patient has been charged with the murder of his wife, whose body was found in the couple's home in Perth's south.

A neighbour found the 87-year-old man disoriented in the driveway of his Guerin Avenue home in Piara Waters on Monday night.

When the neighbour went inside to check on the man's 75-year-old wife, she made the shock discovery.

Police at the Piara Waters property. Picture: 7 News

The elderly woman, who is believed to be the man's carer, had been stabbed multiple times.

Homicide detectives spent most of the night at the crime scene, before the 87-year-old was charged late on Tuesday.

It remains unclear how advanced the man's dementia is.

Officers were called out on Monday night. Picture: 7 News

The couple had lived in the Piara Waters for more than seven years.

Police are still appealing for anyone in the area between 4.30pm and 6.30pm on Monday to call Crime Stoppers on 1800 333 000.

The 87-year-old has been charged over his wife's murder. Picture: 7 News