ST. JOHN'S, Antigua (AP) _ Scotland Yard has joined the investigation into the slayings of an American executive, his wife and two British crew members on a yacht in the eastern Caribbean.

Their bodies were found below deck Saturday on the yacht anchored a mile off the sparsely populated island of Barbuda, 15 miles north of Antigua.

They had multiple stab wounds to their faces, necks and heads, and their hands and mouths were bound with electrical tape, said police Commissioner Edric Potter.

Results of autopsies were pending. The yacht was under guard in Antigua, being examined for forensic evidence.

''Scotland Yard detectives are on the island, quite by coincidence, and are very pleased to help the Antiguan authorities,'' a British Foreign Office spokesman said Tuesday. He spoke only on condition of anonymity, as is British custom.

A team of Scotland Yard investigators already was in Antigua conducting an inquiry into the January 1993 murder of Ralston Samuel, the former head of customs in Antigua.

Police identified the victims as John Cleaver, 58; Patty Cleaver, 52; Ian Cridland, 35; and Thomas Williams, 22.

Police said the Cleavers were originally from California but had been living in Britain, where John Cleaver was an executive at Computacenter Ltd., a micro-computer dealer.

Cridland and Williams, both British, were the crew on the vessel.

The Computacenter Challenger yacht belonged to Peter Ogden and Philip Hulme, chairman and managing director of Computacenter.

The four were last seen Thursday, when they cruised from Antigua to Barbuda and stopped on the western part of the island. The two-island country, a former British colony, is popular among yachtsmen.

Antigua's deputy police commissioner Alvin Goodwin told Britain's Press Association that police were ''looking in the direction'' of a possible drug connection, but had no evidence to back up that theory.

Drug smugglers find the Caribbean a convenient location for dealings between North and South America and Europe.