A witness has come forward at the eleventh hour to shed new light on the brutal unsolved murders of two Sydney nurses in the 1970s.

The 59-year-old man went to police six weeks ago to tell them of a confession by a former friend who was present when Wendy Evans and Lorraine Wilson were killed in the 1970s.

The young women went missing while hitchhiking in Queensland in 1972 and their bodies were found in bushland two years later.

Desmond Edmondstone told the Brisbane Magistrates Court he'd heard the confession 35 years ago, but had been too frightened to come forward, out of fear of retribution.

He said his former friend Larry Charles had told him he'd witnessed the nurses being raped repeatedly and bashed with sticks while tied to a tree in bushland at Murphys Creek, near the southern Queensland city of Toowoomba.