The US Department of Homeland Security is to distribute posters asking for information on the murder of Garda Adrian Donohoe, according to reports.
Detective Garda Donohoe was shot dead by an armed gang during a botched raid on a cash escort in Lordship, Co Louth in January 2013.
The Irish League of Credit Unions is already offering a reward believed to be in the region of €100,000 for information on his killers.
At least one of the attackers is known to have fled to the US shortly after the incident, and the Irish Voice newspaper in New York is now reporting that the Department of Homeland Security is planning to hand out posters in areas he is known to have frequented.
"Investigators believe people living in the Woodlawn/Yonkers/The Bronx area of New York may have information that could assist this investigation. A substantial reward is on offer for information leading to the arrest and conviction of the persons involved," the posters are said to read.
The man was deported from the US to Ireland late last month.
The man, who is understood to be aged in his mid-20s and is originally from south Armagh, had been held in the Hudson County Correctional facility in New York on foot of deportation orders in connection with his irregular immigration status.
He was thought to have been working in the construction industry in New York at the time of his arrest, and is said to be a well-known figure in the local Irish expatriate community.
Sources quoted by the Irish Voice told the newspaper that the suspect "did not keep a low profile" during his time in Woodlawn and Yonkers, and could regularly be seen socialising in Irish bars.