Detectives are following about 1,200 lines of inquiry into the murder of 21-year-old Paul Quinn, a senior Garda officer revealed yesterday.
Mr Quinn, from Cullyhanna, Co Armagh, was beaten to death in October by up to 15 men at farm buildings in Co Monaghan.
His family believes their son was killed by IRA members but Sinn Féin denies any republican involvement. They contend the murder came about after a feud between rival criminal gangs linked to fuel smuggling.
Supt Karl Heller, who is leading the inquiry, said in excess of 1,200 particular lines of inquiry were being followed and more than 400 statements had been taken.
He urged family and friends of those involved in the murder of the south Armagh man to examine their consciences and come forward. After three months of intensive police inquiries on both sides of the Border, public meetings and calls for justice by local politicians, there have still been no arrests.
Supt Heller said the investigation had been "well resourced, professional and very thorough", with officers from the Garda and PSNI working closely together.
"This has involved very close liaison with our colleagues in the PSNI on a daily basis. They have been very good and they have assisted us and facilitated these inquiries taking place north of the Border," he said in an interview with BBC Radio Ulster's Talkback programme.
"Our inquiries haven't dried up. We're still meeting in conference here on an almost daily basis." The superintendent is hoping that those with "pangs of conscience" will not hesitate in coming forward.
"The people who were involved in this crime will have loved ones, whether they be sons, brothers - they have family members. They may have noticed some change in their loved ones' behaviour. They do possess vital information and it's information which will help us solve a crime which was not only a crime against a young man, it's a crime against the community."
The Garda is still waiting on forensic test results which, Supt Heller said, will be a "key building block of the investigation". He appealed for information about a white van, possibly a Toyota Hiace or a Nissan Vanette, with sliding side doors and possibly black bull bars.