Mr O'Brien, 70, of Corwillan, latton, Castleblayney, Co Monaghan, was remanded on bail of €5,000 cash to appear before the Carrickmacross District Court again on 22 May.
The other defendants are Michael Marron, 56, from Taghart, Shercock, Cavan and Raymond McCaughey, 55, from Drumgannus, Broomfield, Co Monaghan.
All three face a single charge that on 27 April, 2012 at Tullyvaragh Lower, Carrickmacross they demanded €100,000 from Michael Heelan with menaces contrary to the Criminal Justice Public Order Act.
The three were granted bail with a surety of €5,000. They were also ordered to hand over their passports, not to contact any witnesses and sign on weekly at their local garda station.
Det Insp Fergus Traynor gave evidence of arresting, charging and cautioning the accused.