The island's political leaders realised the investigation was too complex for local police and called in Scotland Yard.Yes, you read that right. The British police refused to help the investigation until the island authorities surrendered their rights to deal with the case according to Antiguan law.
That help was only given on condition the killers would not face the death penalty.
And for what? Did they think the British public would cheer at the news that we refused to help a former colony because we no longer have the death penalty ourselves, and like dogs in the manger, refused to assist others in giving the murderers what they deserved?