Detectives investigating the murder of a toddler in Australia nearly 50 years ago are trying to locate a family believed to be living in the UK.
Three-year-old Cheryl Grimmer went missing from a shower block at a New South Wales beach in 1970.
The Goodyear family, from Nottinghamshire, provided a statement on the day and police believe they can still help with the investigation.
A 63-year-old man has been charged with Cheryl's abduction and murder.
The girl disappeared from Fairy Meadow beach in Wollongong, a city south of Sydney, on 12 January 1970.
Despite a massive search, police failed to make a breakthrough and the case has remained one of Australia's longest-running mysteries.
Detectives doubt Cheryl's body will ever be found.
However, after the case was re-examined last year a new clue emerged that led to the arrest of a 63-year-old man from Melbourne.
Police believe Peter Goodyear, then aged 37, his wife Mavis, and daughters, Karen, aged six, and Janette, aged five, who were living at the Fairy Meadow Commonwealth Hostel at the time, could still help with the case.
Mr Goodyear worked as a labourer at the John Lysaght Springhill metal works in Illawarra, before he moved his family to Papua New Guinea in late 1970.
The Goodyears, who were originally from Bristol, later returned home to England and were last believed to be living in Oxton, Nottinghamshire.
Det Sgt Damian Loone, of New South Wales Police, said: "We have been making inquiries with authorities in Britain in a bid to find Mr Goodyear, if he is still alive, to determine whether he can still assist our ongoing inquiries.
"To date, those efforts have not been successful."