New hunt in Qld cold case death

Investigators have returned to the central Queensland property where the skull of a girl who vanished in 1972 was found.

Marilyn Wallman, 14, was last seen in March that year, after leaving her home at North Mackay to cycle to school.

Her brothers, who were riding behind her, found her bike on the side of the road lined with cane fields about 10 minutes later.

A fragment of her skull was found in bushland near McGregor Creek, about 40km from where she disappeared, in 1974 but it wasn't identified as her's until January last year.

Specialist police returned to the Mirani property on Monday.

A police spokesman said investigators had been digging at the site, but so far no new evidence had been found.

Officers are due to hold a press conference in Mackay on Tuesday afternoon.