The North's First Minister has accused the Government of dragging its feet over allegations of Garda collusion with republican paramilitaries.
Mr Trimble made the comments as he attended a commemoration for the 25th anniversary of the Kingsmill massacre in which 10 Protestant workmen were murdered as they went home from work.
Speaking at Bessbrook Town Hall in south Armagh, Mr Trimble paid tribute to the dignity and courage of the victims' families.
"Sadly the families have not seen justice done; no one has been made amenable for the murders at Kingsmill. This is all too often the case regarding murders in the south Armagh area," he said.
Mr Trimble said there were well documented suggestions of Garda collusion with the IRA in a number of murders in the south Armagh area during the 1970s. He accused the Government of dragging its feet when it came to investigating allegations of collusion.
Last year he wrote to the Taoiseach demanding a public inquiry into alleged co-operation between the police and paramilitaries.
He said Mr Ahern promised a private investigation conducted by the Department of Justice, but since then nothing has been heard.
Mr Trimble joined 600 people at yesterday's memorial service.
The congregation also included Lord Rogan, the chairman of the Ulster Unionist Party, and two unionist members of the Stormont Assembly from Newry-Armagh, Mr Danny Kennedy and Mr Paul Berry.
The 1976 gun attack was carried out by the Republican Action Group, a cover name for the south Armagh unit of the Provisional IRA and the anguish was still etched yesterday on the faces of close relatives of the victims.
A central figure at yesterday's remembrance was 56-year-old Mr Alan Black, the only survivor of the attack, who suffered 18 bullet wounds to his body.
"This service and act of remembrance is for the lads, good, honest, decent fellows who were so callously taken from us on that dreadful night," said Mr Black.
"I survived, along with Richard Hughes, the only Catholic on the works minibus, another very decent man. But we will never forget the 10 lads who never made it home that night."
The Kingsmill massacre came 24 hours after the sectarian killing of six Catholic men in separate incidents at Whitecross in South Armagh and Ballydougan, near Lurgan.
Earlier, on New Year's Eve, 1975, the IRA killed three Protestants in a no-warning bomb attack on a Gilford, Co Down, public house.