Watch Key to Human Bones Mystery Vital clue: A watch found near bones at Brooklyn. Photo: NSW Police Police hope a blue and silver wristwatch may hold the key to solving the mystery discovery of human bones in bushland north of Sydney. A mother and her 13 year-old son were walking along a bush track near Brooklyn on the Hawkesbury River last Thursday when they came across a human skeleton at the base of a cliff. The pair walked to a nearby fish and chip shop to phone police, who conducted a canvas of the area and found the old-style Citizen watch near the decomposed body of a man. He was tall and wore a black sweater vest and dark trousers. But police have few other clues as to who he is, how he died and why his death went unnoticed for so many years. ""We are hopeful someone who has a missing loved one will recognise this watch and get the closure they deserve," Detective Inspector Ian Mitchell said. Police are trawling through missing persons records and have made contact with the manufacturer of the watch. The bones will be forensically tested as well as assessed by an anthropologist to determine how old they are. Based on the heavily decomposed state of the man's body, Detective Inspector Mitchell said the remains had lay in bushland for ""some time"." ""A lot hinges on the anthropologist's report because it will give us a narrower date range for the remains and then we can really concentrate on particular elements,"" he said. Suicide could not be ruled out, considering the body was found at the base of a cliff, but police are keeping an open mind. "It's too early to make any assumptions as to the cause of death or the identity of the person," Detective Inspector Mitchell said. The watch has a blue face and silver band. The time has stopped at 12.37 and the date at Saturday the 14th.