The family of a Perth father, who was found unconscious outside a busy shopping centre, has made a desperate plea for help to solve the mystery incident.

Romuad Menezes, 57, is in the intensive care unit at Royal Perth Hospital in a serious condition with critical head injuries, including a fractured skull and a massive blood clot on the brain.

Doctors told 9NEWS his injuries are not consistent with a simple fall, and police are now investigating whether the father of two was assaulted.

Mr Menezes remains in a critical condition. (9NEWS)

Mr Menezes was found by police around 11.30PM on Saturday, on the corner of Sussex Street and Albany Highway outside The Park Shopping Centre in Victoria Park.

Kensington Police said the father of two may have been lying there, unassisted, for up to two hours.

His wife, Rochelle Menezes, said the 57-year-old is not a confrontational person.

“All I want is some answers for my daughters and myself,” she said.

“If someone can just come forward and tell police what happened, that’s all we want to know.”

The father of two was found outside The Park Shopping Centre on Saturday night. (9NEWS)

Police also want to speak to the occupants of a white Hyundai Hatch and a silver Hyundai van that were seen parked in the car park at the time.