Whiston boys' 1980 murder: Police investigation 'lacked thoroughness'
The investigation of the murders of two schoolboys 38 years ago "was not as thorough as it could have been", Merseyside's chief constable has said.
John Greenwood and Gary Miller, both 11, were beaten and hidden on a rubbish tip in Whiston, Merseyside in 1980. A man was acquitted of murder in 1981.
New leads reopened the case in 2016.
Apologising to the boys' families, Chief Constable Andy Cooke said there was insufficient evidence to continue with the new investigation.
A dog walker found the school friends at the site of a disused colliery on Pottery Lane, which is now Stadt Moers Park, at about 19:20 BST on 16 August 1980.
They both later died at Whiston Hospital as a result of head injuries, post-mortem examinations revealed.
Speaking after a meeting with their families, Mr Cooke said he understood that they were "frustrated and disappointed by what they see as inadequacies and failings of the original investigation".
"The investigation team at the time provided sufficient evidence to charge a man with the murder of the boys and he stood trial and was subsequently acquitted.
"Having carried out a number of cold case reviews and following the reinvestigation of the murder, it is fair to say that the investigation was not as thorough as it could have been, or in line with the investigation standards expected of policing today."
He added the force offered their "sincere apologies to the families of John and Gary" and remained "committed" to finding whoever killed them.
However, he said the force had submitted a file containing the new evidence it had found to the Director of Public Prosecutions (DPP), but after "careful consideration, the DPP made the decision not to authorise the next steps".
He added that the DPP "acknowledges that this is a tragic case and has said that in the event that the ongoing police investigation yields sufficient compelling new evidence, he would reconsider his decision".