WA man's death now a suspected homicide

The death of a 31-year-old Perth man last month is now being investigated as a suspected homicide.

Friends found Michael Watson unconscious at his home on Grove Rd in Lesmurdie on November 24.

He was rushed to St John of God Hospital but died two days later.

Police are now looking for Mr Watson's Samsung Galaxy Note 4 mobile phone, which may have been discarded and picked up by a member of the public.

Detectives also want to speak to anyone who had contact with Mr Watson in the days leading up to his death and the driver of a blue VT Holden Commodore, which was seen at the house the day before he was found.