Question: Gary Donnelly was a former prisoner of which dissident Irish faction?

Context paragraphs:
Gary Donnelly (Irish republican): Gary Donnelly is an Irish republican, former Real Irish Republican Army (Real IRA) prisoner, and as of May 24, 2014, an elected member of Derry and Strabane District Council.

1987 Tokyo Indoor – Doubles: Mike De Palmer and Gary Donnelly were the defending champions, but Donnelly did not participate this year.  De Palmer partnered Paul Annacone, losing in the quarterfinals.

1987 Schenectady Open – Doubles: Gary Donnelly and Gary Muller won the title, defeating Brad Pearce and Jim Pugh 7–6, 6–2 in the final.

Gary Donnelly: Gary Donnelly (born June 3, 1962) is a former professional tennis player from the United States.

Real Irish Republican Army: The Real Irish Republican Army or Real IRA (RIRA), is a dissident Irish republican paramilitary organisation which aims to bring about a united Ireland.  It formed in 1997 following a split in the Provisional IRA by dissident members, who rejected the IRA's ceasefire that year.  Like the Provisional IRA before it, the RIRA sees itself as the only rightful successor to the original Irish Republican Army and styles itself as "the Real Irish Republican Army" in English or "Óglaigh na hÉireann" in Irish.  It is an illegal organisation in the Republic of Ireland and designated as proscribed terrorist organisation in the United Kingdom and the United States.

1987 Volvo International – Doubles: Peter Fleming and John McEnroe were the defending champions but they competed with different partners that year, Fleming with Gary Donnelly and McEnroe with his brother Patrick.

Óglaigh na hÉireann (Real IRA splinter group): Óglaigh na hÉireann (ONH; ] ) is the title taken by a small dissident Irish republican paramilitary group that has taken part in the dissident Irish republican campaign.  The organisation started carrying out attacks around 2009 and was formed after a split within the Real IRA.

1987 WCT Scottsdale Open – Doubles: Leonardo Lavalle and Mike Leach were the defending champions, but Lavalle did not participate this year.  Leach partnered Gary Donnelly, losing in the first round.

Sergei Aksenov: Sergei Alexandrovich Aksenov (Russian: Серге́й Алекса́ндрович Аксёнов ; born April 3, 1971) is a Russian political dissident, publicist, former prisoner, member of National Bolshevik Party since 1997, cofounder of coalition The Other Russia and one of the leaders of the political party The Other Russia.

1988 OTB Open – Men's Doubles: Gary Donnelly and Gary Muller were the defending champions, but did not participate this year.

Supporting paragraphs: Gary Donnelly (Irish republican) Real Irish Republican Army
Answer: Real Irish Republican Army