He was born in a slum district in Grenville Street in Dublin's north inner city, the second of twelve surviving children of Patrick Cahill, a lighthouse-keeper, and Agnes Sheehan.
[3] At age 16, he was convicted of two burglaries and sentenced to an industrial school run by the Oblates of Mary Immaculate at Daingean, County Offaly.
With his brothers, he continued to commit multiple burglaries in the affluent neighbourhoods nearby, at one point even robbing the Garda Síochána depot for confiscated firearms.
Finally, Lord Mayor of Dublin Ben Briscoe paid a visit to Cahill's tent and persuaded him to move into a new house in a more upscale district of Rathmines.
He was also involved in stealing some of the world's most valuable paintings from Russborough House (1986)[5] and extorting restaurants and hot dog vendors in Dublin's nightclub district.
"[7] As a result, the Gardaí set up a Special Surveillance Unit (SSU), nicknamed "Tango Squad", to specifically target and monitor Cahill's gang on a permanent, 24/7 basis.
[7] The SSU also placed a direct presence on the estate at Cowper Downs, positioning a surveillance unit in the home of developer John Sisk, whose house backed onto Cahill's.
[7][8] In early 1993, John "The Coach" Traynor, met his boss Cahill, to provide him with inside information about the inner workings of the National Irish Bank (NIB) head office and branch at College Green, Dublin.
[9] With all gang members from the Lacey kidnapping released on bail, on 18 August 1994, Cahill left the house at which he had been staying at Swan Grove and began driving to a local shop.
The UVF unit in question had recently attempted a bomb attack on a south Dublin Irish pub which was hosting a Sinn Féin fund-raiser on 21 May 1994.
The UVF operatives had been prevented from entering by pub doorman and Volunteer in the Provisional IRA's Dublin Brigade Martin Doherty, who they instead shot dead.
[12][13] The IRA further alleged that Cahill had been involved in selling the stolen Vermeer paintings from Russborough House to the UVF Mid-Ulster Brigade led by Billy Wright, alias "King Rat".
[16] Another theory surfaced after the publication of Paul Williams' The General, which claims to have insights from Garda cold case investigators who were still looking into Cahill's murder.
A further incentive was provided by Gilligan and Traynor, from whom the Provisionals allegedly demanded and received a considerable sum in exchange for Cahill's assassination.
[18] In 1984, Cahill had bought his growing family a house on the Cowper Downs development, on the southside of Dublin, paying IR£80,000 cash despite having no paid formal employment since he left his first and only job in 1969.
[19] In 1998 John Boorman (who had lived in Ireland for nearly 20 years) directed a biographical film titled The General, starring Brendan Gleeson as Cahill.