Garda Commissioner Martin Callinan has said gardaí know the type of people they are dealing with in the investigation into the murder of Detective Garda Adrian Donohue, and they will not give up.

Det Garda Donohoe was shot dead two weeks ago during an armed robbery in a credit union in Co Louth.

Commissioner Callinan was in Dundalk for a case conference on the investigation.

He said increased resources and more detectives have been assigned to the case in the last two weeks.

He also said 360 statements have been taken and 1,125 lines of enquiry are being pursued.

Commissioner Callinan said 1,500 questionnaires have been circulated and 140 pieces of CCTV footage and 300 exhibits are being examined.