SYDNEY (AFP) - An American diver is believed to be the latest victim of a fatal shark attack in Western Australia, police said Saturday, just days after a man vanished while swimming in waters off the state capital Perth. The 32-year-old was on an unaccompanied dive off Rottnest Island off Perth when witnesses waiting for him on their boat noticed something amiss. A least one of them saw a large amount of bubbles, police sergeant Gerry Cassidy told AFP. And a short time later the deceased surfaced with obviously traumatic and fatal injuries. One witness later saw a three-metre (10-foot) great white shark in the water. Police were called and retrieved the body, believed to be that of a United States citizen studying in Australia, from the water about 500 metres (yards) northwest of Little Armstrong Bay.