Two RUC officers murdered in an IRA ambush were killed after disobeying an order not to cross the border into the Irish Republic, it has been claimed.
Chief Superintendent Harry Breen and Superintendent Bob Buchanan were gunned down in Co Armagh in March 1989 as they returned from talks with a top Garda officer in Dundalk, Co Louth.
The Smithwick Tribunal in Dublin, in its first day of witness evidence, heard then RUC chief constable John Hermon warned four days before the killings that they did not need to cross the border.
A former assistant chief constable, who cannot be named, said he then ordered the men not to leave Northern Ireland. "It still lives with me the fact that I told them not to go," he said, speaking from behind a blue screen to protect his identity.
"They disobeyed an order and were killed." He added: "It wasn't the first time somebody disobeyed an order and they finished up being killed."
Mr Breen and Mr Buchanan were two of the highest-ranking RUC officers killed in the Troubles. They had travelled to the Republic to discuss a possible joint RUC/Garda police operation.
The tribunal, established in 2005, is investigating allegations that Garda officers in the Republic or a civilian working in the force colluded with the IRA in the murders. The tribunal, headed by Judge Peter Smithwick, has cost eight million euro so far.
The assistant chief constable, whose command covered counties Antrim, Down and parts of Tyrone, said he spoke to Mr Hermon before travelling to Armagh on March 16 to meet the RUC officers - four days before they were murdered.
"I asked both men to give me a promise that they would not go across the border," he said. "And they did (give a promise), because there was no necessity in it."
After the hearing, John McBurney, solicitor for the Breen family, said it was unlikely the officers would have ignored the order. "These men clearly both had concerns about travelling to these meetings, Mr McBurney said. "For them to be given the opportunity not to go, is not something to my mind that would be ignored, that would be challenged, that would be contradicted."