GARDAI have seized documents from the home of murder victim John Kerins in a bid to unravel the background to his shooting.
The former garda was gunned down in the early hours of Friday as he lay on a couch at his home outside Bailieborough, Co Cavan.
Officers carried out an extensive search of his house at Cornaveagh after members of the technical bureau completed their forensic examination.
A senior detective said they had taken away documents and other "bits and pieces" for a more detailed examination in the hope they might provide clues to Mr Kerins' recent dealings or business transactions.
Gardai are also examining footage from CCTV cameras outside a local garage and several pubs plus private residential monitors that also covered part of the nearby road.
They are trying to identify vehicles that were in the area last Thursday night or early Friday morning.
Officers believe Mr Kerins (48) knew his killer and either allowed him into the house or was waiting for him to arrive.
There was no sign of forcible entry and gardai said the victim was in a relaxed position on the couch with a TV remote control by his side. Over the past couple of days gardai have interviewed potential suspects from the area.
Officers say officially they are keeping an open mind on the motive behind the shooting, but their main line of inquiry is that Mr Kerins, a retired fraud squad detective, was targeted by a drug trafficking gang. The father of three was suspected for some time of being on the periphery of the gang, but they believe he was never a major player.
Detectives think the gang may also have been responsible for the disappearance last June of Mr Kerins' near neighbour and friend, Gerard Daly, who moved to Cornaveagh from Tallaght in south Dublin.
Both men had a keen interest in dog breeding.
Meanwhile, Garda Commissioner Martin Callinan yesterday condemned as "appalling" the shooting of Mr Kerins, who was discharged from the force on medical grounds in 2010 after being ill for the previous five years.
Speaking at the Garda College in Templemore, Co Tipperary, where six members of the force and a retired superintendent received Scott medals for bravery, Mr Callinan pledged that the force would explore every avenue in tracking down the killers.
He said it was their job to use their skills to bring those responsible to justice.