A suspected informer with links to a former leading member of Saoradh in Derry was quizzed by police as part of an investigation linked to the killing of Lyra McKee.
The republican has not been seen locally since the end of last week.
A spokesman for Saoradh, which has the support of New IRA prisoners, said he was not a member of the party but was "on the periphery of some activism by local members".
Lyra McKee was shot dead by the New IRA as she observed rioting in the Creggan area of Derry in April 2019.
Informed sources say the suspected informer, named last night as Billy Elliot, was one of several people questioned by police investigating the rioting.
It is also claimed he was filmed in the area by an MTV crew fronted by British broadcaster Reggie Yates and spoke on camera to the documentary makers.
The Irish News understands he presented himself to police and was released hours later without charge.
He is thought to be the first suspected informer linked to Saoradh to be exposed since Dennis McFadden's cover was blown almost two years ago after an MI5 sting targeted the New IRA.
The information provided by McFadden, who is believed to be under the protection of British state agencies, was a serious setback to the paramilitary group.
Sources close to the New IRA have claimed Mr Elliot was under suspicion in recent months and was "exposed" after being challenged by a family member.
A statement on Facebook last night said he "disappeared from the family home several days ago after making it known to a family member that he was being pressured by British security services".
"It now appears that he was coerced into collaborating with these individuals," it said.
"As many will already know, Billy suffered from long-standing mental health problems, addiction issues, and illiteracy.
"In outlining these facts, we do not wish to give the impression that they in any way excuse his behaviour."
The statement added: "This week has been incredibly challenging and traumatic for our family and we appeal to anyone who finds themselves being pressured in this way to seek help and reach out to a local community representative.”
