Scotland Yard have launched an international appeal for Adams, 59, who is a member of the infamous Adams family crime gang and believe he may be on the run in Spain or Holland.
He is believed to be in hiding with his 54-year-old wife Constance, after the pair were linked to a shooting in Clerkenwell, north London three days before Christmas in 2013.
The shooting took place at 10am when a man and woman approached a motorist who was sitting at the wheel of his black BMW X5 car and shot him in the chest in what was widely thought to have been a gangland hit.
The victim survived the attack, but spent more than a month recovering in hospital.
A European arrest warrant has now been issued for Adams and his wife, who as far back as 2001 were reported to have a property in Torremolinos on the Costa del Sol.
Detective Inspector Glenn Butler, from the Metropolitan police's Trident and Area Crime Command, said in a statement: “I am appealing for anyone with information about where the pair are now living to contact us as a matter of urgency.
“It is apparent, by the nature of this violent crime that they need to be traced and interviewed by police. We treat any information that is passed to us with the greatest of confidence.”
Adams, who is known as Patsy, is the younger brother of feared underworld crime boss, Terry Adams who was jailed in 2007 for seven years after being found guilty of money laundering.
Nicknamed the A-Team, the criminal enterprise headed up by Terry, Patrick, and another brother Sean, since the 1970s has been linked to a protection racket, drugs and armed robbery.
The brothers who were brought up in Barnsbury area of Islington ran a crime syndicate that has been linked to more than 20 gangland murders.