The man who led the investigation into the death of Pakistan cricket coach Bob Woolmer went to the Caribbean to try to tackle its gang violence problems.
Mr Shields investigated Jamaican 'Yardie' crime while at the Met
Jamaica's Deputy Police Commissioner is a former Scotland Yard detective chief superintendent. He was a senior officer in the specialist crime directorate.
He had already been in Jamaica with Operation Trident, investigating London's black-on-black gun crime.
A police officer for more than 30 years, Mark Shields was head of City of London Police's special branch from 1987 to 1990.
Later roles included a spell in Germany liaising on organised crime for British police and as a member of City of London's fraud squad.
After spending time with Essex Police, he became a detective superintendent in the Yard's serious and organised crime unit in 2001. There he managed investigation teams combating gun crime, drug trafficking and gang-related "contracts to kill" in London.
He was involved in the investigation into the alleged Victoria Beckham kidnap plot.
But it was in 'Yardie' violence (involving Jamaican or black British drug gangs) where he gained most expertise.
In May 2002 he helped investigate a shooting in the rural district of Kraal in Jamaica, and later assisted an inquiry into the alleged abduction of two men.
Mark Shields' earlier work in Jamaica did not go unnoticed
The work did not go unnoticed and it was decided to appoint Mr Shields as deputy commissioner in Jamaica as part of a long-term secondment from Scotland Yard.
British officers have been deployed to the Caribbean in the past as advisers. But Mr Shields has a formal position, with Jamaican officers under his command.
It was hoped he would be able to help stop the capital's Yardie problem at source, and provide a useful weapon in the fight against police corruption in Jamaica.