Gardai are operating alongside PSNI officers in joint door-to-door inquiries in south Armagh as they gather intelligence on members of the crime gang suspected of murdering Det Gda Adrian Donohoe last January.
The investigation is carried out under an agreement reached by the two forces in tackling cross-border crime.
The Donohoe murder investigation is regarded as a "slow burner" as the two police forces build up a dossier on the suspected criminals believed to have been involved in the shooting and their associates.
Officers have seized guns, stolen vehicles, computers and mobile phones as they crack down on a number of gangs operating in the Border region.
Two men have been questioned by gardai in relation to suspected links with the gang.
Gardai are satisfied that five members of the gang were present when Det Gda Donohoe, a father of two, was shot dead.