Although born to a wealthy family, Tyrell had previously served a prison sentence for his involvement in smuggling marijuana in Guadaloupe and Antigua during his youth. He eventually became a well known and colourful figure in the island's yachting circles and later met his future wife Julie Paterson, then the owner of a local yacht charter service.
After becoming married in 1994, he and his wife cooperated on a large scale drug trafficking operation worth $10 million. Along with his friend and criminal associate Frederic Fillingham, a former boatbuilder and sailor who had fled the United States after receiving parole on drug smuggling charges, Tyrell contacted Robert Kavanagh who used his connections with Colombian drug cartels to secure the delivery of 396 kg of cocaine for Tyrell's organization.
While he was apparently undetected by the Drug Enforcement Agency, Tyrell long had a reputation for bragging of his criminal activities and operated freely within Antigua while continuing to hold meetings with known drug traffickers (including an unidentified member of a Colombian drug cartel) and recruiting members of the drug ring.
However, while thought to be safe from local officials, he was eventually discovered by British authorities and his activities soon came under Operation Eyefull, one of the largest surveillance operations ever undertaken by police and custom officials. Keeping a close watch over Tyrell and Paterson for several months, they were eventually observed unloading their cargo on a deserted beach on the Isle of Wight.
Arrested by officers of the Customs Law Enforcement and National Crime Squad, Tyrell and four others were tried at Snaresbrook Crown Court and convicted of drug trafficking charges. Tyrell was sentenced to 26 years imprisonment while his accomplices Robert Kavanagh and Didier Andre Lebrun received 24 and 19 years imprisonment respectively Julie Paterson was convicted of additional charges of money laundering and sentenced to 24 years imprisonment, the longest sentence ever for a female drug trafficker.