Former terror leader Johnny Adair last night said he was "gutted" following the sudden death of his son Jonathan in Scotland.
Adair Jr (32), died at Templehill in the Ayrshire seaside town of Troon.
Police said that his body was discovered at a property on Saturday afternoon and they were initially treating his death as "unexplained".
He was a drug user and had a conviction for dealing heroin.
Jonathan, who was known as 'Mad Pup' in the media, was only released from prison recently for driving offences.
On Sunday night, Johnny 'Mad Dog' Adair (52), a former leader of the UFF terror group, said he was "gutted" at the loss of his son.
He said that he was too upset to say anything further.
A post-mortem examination will be carried out and a report will be submitted to the procurator fiscal in Scotland.
A Police Scotland spokeswoman said: "At around 5.15pm on Saturday police received a report of a body of a man having been found within a property in Templehill in Troon.
"A post-mortem will be carried out in due course to establish the exact cause of death. Officers are treating it as unexplained at this time."
The Adair family moved to Ayrshire after being forced to flee Northern Ireland in 2003 following a series of murders which were linked to a loyalist feud.
When he was 18 and still living in Belfast, Jonathan Adair was shot in both legs in the lower Shankill area.
The dad-of-two was set to face drugs charges in January and had been in and out of custody for other drugs, driving and disorder offences in recent years.
The drugs case against him was called at Kilmarnock Sheriff Court on Friday.
His legal representative lodged a not guilty plea.
'Mad Dog' served 16 years for directing terrorism before being freed under the Good Friday Agreement.
Friends and relatives last night paid tribute to Jonathan on Facebook. Emma Skelly said: "Thinking of Gina, Natalie, Chloe, and rest of the Adair family, who have lost their brother and a son.
"Life's so unfair... thoughts and prayers are with his two children also."
A cousin, Jim Holmes, said he was "gutted to hear of the sad loss".
Angela Robertson said: "Jonathan Adair you where the funniest guy I've ever met.
"Such sad news another young life took just like that. RIP big man."