A file of evidence linking serial child killer Robert Black to the murder of Genette Tate has been submitted to prosecutors in England.
The Scottish-born sex attacker, 68, died in non-suspicious circumstances in Maghaberry high security jail in Northern Ireland.
He was serving multiple life sentences for the murders of four schoolgirls in the 1980s and a number of other crimes.
Black, a delivery driver who stalked the roads of the UK searching for victims, has long been suspected of murdering 13-year-old Genette.
Genette, a newspaper delivery girl, vanished from a rural lane in Aylesbeare, Devon, in August 1978. Her body has never been found.
A spokesman for Devon and Cornwall Police confirmed the evidence file had been submitted to the Crown Prosecution Service (CPS).
"The major part of a file concerning this matter has now been sent to the CPS for a charging decision," the force spokesman said.
"This has been a long and complex enquiry and we have kept the family of Genette Tate informed throughout.
"We now await further direction from the CPS on how this may progress in the coming weeks."
Earlier this year, police said Black was likely to have been charged with Genette's abduction and murder.
Black first became a suspect in Genette's murder in 1994 and was interviewed by Devon and Cornwall Police in 1996.
A reinvestigation into Genette's murder began in 2014 following a court of appeal ruling against Black in 2013.
Devon and Cornwall Police have had a team of 10 working on the case extensively for the past two years.
The team is understood to have identified new potential witnesses in the case.
Detective Superintendent Paul Burgan, of Devon and Cornwall Police, previously said the CPS were "weeks" away from charging Black when he died.
He confirmed the file would still be submitted for a charging decision for Genette's family, describing Black's death as "a complete shock".
"Robert Black was ultimately an aggressive, predatory paedophile," Mr Burgan added.
"He was every parent's worse nightmare. He was a danger to children.
"Robert Black did kill on a number of occasions around the country and we would attest that Genette was one victim in that reign of terror he committed from 1978 until his arrest in 1990."
Black's offending ended in 1990 when he was caught red-handed by police with a barely alive six-year-old girl hooded, bound, gagged and stuffed in a sleeping bag in the back of his van in the Scottish village of Stow. He had sexually assaulted her moments earlier.
Once in custody, detectives were able to link the predator to a series of unsolved crimes in the previous decade.
In 1994, Black was found guilty of three child murders in the 1980s - those of 11-year-old Susan Maxwell, from the Scottish Borders, five-year-old Caroline Hogg, from Edinburgh, and Sarah Harper, 10, from Morley, near Leeds - as well as a failed abduction bid in Nottingham in 1988.
In 2011, he was found guilty of the 1981 murder of nine-year-old Jennifer Cardy, from Ballinderry, Co Antrim.