THE parents of a man who died from a stab wound after a row with his partner have publicly renewed their call for an inquiry after what they term a "whitewash" by police.

Colin Marr, 23, died in July 2007 from a single stab wound following a domestic row with his fiancee Candice Bonar in Lochgelly, Fife.

Fife Constabulary initially treated the death as suicide, but Mr Marr's mother and stepfather, Margaret and Stuart Graham, have continually criticised the initial handling of the case. The former police force has previously formally apologised for their immediate response to the death.

However, Mr and Mrs Graham believe this did not go far enough. Among their complaints is what they see as a lack of integrity, with seven individuals involved in the investigation taking early retirement before a formal investigation or disciplinary action could be taken.

The Grahams said: "The actions taken by Police Scotland, in dealing with the glaringly obvious attempt by Fife Police to whitewash the actions of their officer(s), have caused further delays in dealing with our substantiated issues, and will most likely allow another officer to retire before facing accountability. This fight is not based upon emotion but down to the simple and fundamental fact that we have been failed in the worst way possible"

Ms Bonar, who now lives in Australia, said Mr Marr stabbed himself when she told him she was leaving him.

After a fatal accident inquiry in 2011, Sheriff Alastair Dunlop said he could not decide if the death was suicide or homicide, but said this should not undermine the presumption of innocence of Ms Bonar.

Mr and Mrs Graham want to see "immediate action" against the Senior Investigating Officer who led the inquiry from October 2008.

They added: "We want to see a full investigation, independent of police, into the actions of Fife Police on the night of our son's death and in the aftermath, to make accountable those who failed in their duty."

Mr Marr's family have been supported by Scottish LibDem leader Willie Rennie in their calls for further investigation.

He said: "I would urge Police Scotland to address this once and for all and authorise a transparent and thorough investigation."

A Police Scotland spokesman said: "The failings of Fife Constabulary in relation to the initial investigation into the death of Colin have been acknowledged previously and it is clear that the initial investigation was not of the standard expected."

A review by the Police Complaints Commissioner for Scotland found the initial complaint, which resulted in a formal apology, had been handled appropriately. A second complaint investigation has now been referred to the Police Investigations and Review Commissioner.

The spokesman added: "Police Scotland have communicated this position to Mr and Mrs Graham and we have identified a single point of contact to enable communication in relation to any additional information they require or complaints they wish to raise."