Eoghan and Theresa O'Neill said they were relieved to be reunited with their younger son Shane, 23, who was freed on police bail yesterday afternoon pending further inquiries.
Mr O'Neill, whose 27-year-old brother was shot during a police raid last Monday on a house in Hammersmith, west London, was released from Paddington Green high security police station at around 3pm.
His parents said: "Our eldest son, Diarmuid, was never arrested; he can never be tried, nor can he be acquitted or convicted other than by the press who have not waited to have a full and proper picture before judging him. Instead, those who accused him took the law into their own hands and killed him.
"Diarmuid was a kind, unselfish and loving son whom we loved dearly all his life. If he had been tried, and in turn convicted, we would still have loved him deeply and supported him as a family.
"We thank everyone who has sought to understand the whole situation in which our family finds itself, and who know that we will miss Diarmuid desperately and we will grieve for him for the rest of our lives."
Scotland Yard said the other four men arrested on Monday remained in custody.
Shane was arrested at a house in Averil Street, Fulham, which he shared with his sister Siobhain, at the same time as police were raiding the house in Glenthorne Road, Hammersmith, where Diarmuid was fatally wounded by armed officers.
Three other suspects were detained at the Hammersmith address and in Fulham. Another man, a 21-year-old engineer employed at Gatwick Airport, was arrested in another raid on a house in Crawley, West Sussex.
It was in a further raid on a warehouse in north London that police recovered a record haul of 10 tonnes of home- made explosives, two pounds of Semtex, other bomb-making equipment and guns and ammunition.Reuse content