A series of failures by police to follow up key recommendations could have led to breakthroughs in multiple cold cases while glaring errors hindered crucial lines of inquiry, an inquiry has been told.
The blunders were laid bare during a Special Commission of Inquiry into suspected gay hate deaths in Sydney, part of hundreds of unsolved homicides languishing on file.
Unsolved homicide squad Detective Chief Inspector David Laidlaw conceded his team had no record of many of the cold cases being examined and had made no communication with the hate crimes unit over the course of the hearing.
The inquiry heard a 2005 recommendation to obtain a DNA sample from a person of interest in the unsolved murder of William Dutfield was ignored.
By the time police eventually tried to obtain a sample in 2008 the person had died.
Other documents tendered to the court showed a series of inaccuracies and "obvious errors".
Written evidence relating to the case of Peter Baumann - a man who disappeared from Sydney in the 90s with his body never to be recovered - made references to post-mortem results.
Det Chief Insp Laidlaw conceded the evidence was "just plain wrong".
Counsel Assisting James Emmett SC said the inquiry had identified a number of cases in which lines of inquiry were identified that were "either not implemented or not implemented for a decade or more".
In another startling admission, Det Chief Insp Laidlaw said his team "quite possibly" did not look at any cases at all between 1970 and 2009 and agreed he had "absolutely no idea as to the dimension of the problem".
The inquiry was earlier told that out of more than 400 cold cases, 201 were identified for reinvestigation.
Det Chief Insp Laidlaw was unable to say how these cases were selected, where the list could be found or whether anyone had been tasked with the reinvestigations.
"Did you just pick them at random?" Mr Emmett asked.
Only 76 cases were found to have been reviewed between 2009 and 2017 despite a team of 38 full-time officers working within the NSW unsolved homicide team.
Mr Emmett said at the current rate it would take the detectives about 50 years to review all cases on file.
"So will it be, what, 40 to 50 years on your current track to review them all?" he asked the chief inspector and 38-year veteran of the force.
Commissioner John Sackar earlier asked Det Chief Insp Laidlaw why an urgent audit of all unsolved cases had not taken place.
"These are all people's lives and people's family's lives," Justice Sackar said.
"Am I missing something, or do I detect that the police as an institution don't rate unsolved homicide too highly in terms of priorities?"
The inquiry was told that before 2004 there was no system in place for the management or review of unsolved homicides.
Despite relying on a tracking file as a "live document" to keep recording unsolved homicides and suspicious deaths, the inquiry was shown that the last matter on file was from August 2016.
Det Chief Insp Laidlaw said the official record management system used by his team since it was established in 2004 was still a work in progress when asked why no data had been recorded for the past seven years.
The inquiry was told at least six high-profile suspected gay hate cold cases currently being examined by the commission were not recorded on tracking file.
Det Chief Insp Laidlaw was unable to explain why the case details of William Allen, Robert Malcolm, James Meek, Richard Slater, William Rooney and Carl Stockton - all killed in brutal assaults during the 1990s - were seemingly absent from the squad's official working document.
