KRW Law is making a formal submission to the Government to probe Malachy Finegan's relationship with the police.
The priest is alleged to have committed a litany of abuse against children over decades, both as his time as a teacher and president of St Colman's College in Newry and later as parish priest at nearby Clonduff.
Kevin Winters of KRW Law (pictured above) told the PA news agency that his call for an inquiry under the 2005 Inquiries Act comes after the Crown Solicitors' Office, responding on behalf of the Police Service of Northern Ireland, said it could neither "confirm or deny" that Finegan had been an informant.
Mr Winters said rumour and speculation that Finegan, who died in 2002, may have avoided prosecution by giving information.
"Malachy Finegan was involved in the abuse of boys on an industrial scale," he said.
"Many, many complaints were filed with the police over a 25-year period, there were investigations and they all came back to nought.
"So for many years people were asking why that was allowed to happen, why were there no directions to prosecute."
He added: "Anecdotally there was word that Malachy Finegan may have been an informant and we wrote to the PSNI asking them to confirm or deny that and they came back and said they would reply the policy of NCND (neither confirm or deny), so it is against that background that we wrote the secretary of state demanding an inquiry.
"There were many boys at St Colman's College who came from the republican heartlands of South Armagh and there is anecdotal evidence to suggest that in fact Malachy Finegan had some form of contact with police in relation to those boys and would have provided information."
Mr Winters said the NCND policy is inapplicable in the Finegan case.
"Malachy Finegan is dead almost 20 years there is no reason to hide behind that policy," he said.
"Many people are demanding answers and they are entitled to them."
He said victims had a "legitimate expectation" to be told the truth.
"So it is wrong for the police to hide behind that blanket policy."
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