The family of forestry worker Seamus Ludlow has renewed its call for a public inquiry into his murder in 1976.
Mr Ludlow, who was shot dead by a loyalist gang on the border after leaving a Dundalk pub, is currently the subject of a private inquiry and an inquest.
Relatives of the 47-year-old bachelor believe that he was targeted by a gang of four loyalists, two of them members of the Ulster Defence Regiment.
The family last week received a copy of the original garda file on the shooting from Louth County Coroner Ronan Maguire, who is due to conduct an inquest into the killing later this year. But the murder victim's nephews Michael Donegan and Jimmy Sharkey last night expressed disappointment with the contents of the file.
Both men, who have led the campaign for a public inquiry into the murder, claimed that sections of the file were "barely legible" because of frequent photocopying.
They also said that the files contained little new information that could lead to the conviction of their uncle's killers.
"The file is full of contradictions and half-truths. It is very unsatisfactory and disappointing for the family because we still feel that we are being kept in the dark. We want to know exactly what happened, why the garda investigation was abandoned after just 19 days and who ordered it to be abandoned," Mr Donegan said.
He also said he believed the coroner's work would not be complete without the original RUC file, Mr Ludlow's clothing and the bullets used.
It has emerged in recent years that the RUC knew the possible identity of the killers but kept the information from investigating gardai until 1979.
