ROAD TOWN, British Virgin Islands (AP) —Murder defendant William Labrador might have slept with Lois McMillen the night before she was killed, but a Tortola jury won't hear about it.

Judge Kenneth Benjamin ruled that a potentially important prosecution witness won't be allowed to testify about a conversation he allegedly overhead between defendant Alexander Benedetto and his lawyer. The judge decided that any comments Benedetto might have made about the relationship between Labrador and McMillen were protected by attorney-client privilege.

McMillen, 34, was found dead on a Tortola shore on Jan. 15, 2000. She had been vacationing on the island at the time. Benedetto, Labrador, and co-defendants Michael Spicer and Evan George were charged with murder shortly afterwards and have been jailed since.

Luis Reveiz, a former FBI agent working for both the McMillens and prosecutor Terrence Williams, claims that Benedetto told one of his lawyers within Reveiz' earshot that someone had sex with Lois McMillen the night before her body was found. Reveiz said it was "apparent" to him that Benedetto was talking about Labrador. He informed Williams about the incident in a letter in October, which was reviewed by Court TV last week.

The investigator might have lent support to testimony from the prosecution's star witness, former Labrador cellmate Jeff Plante. He is expected to testify that Benedetto said Labrador had McMillen up at the defendants' house and accused him of having more complicity in the crime than the others.

But another prosecution witness did help their case on the stand Monday. A forensic expert from Britain said the suggestion that McMillen took her own life was "laughable." The defense has raised suicide as an alternate explanation for the artist's death.

Prosecutors have argued that one of the defendants held McMillen face down in shallow water until she drowned.

The four defendants, who have pleaded innocent, deny being with McMillen the night she died, although they said they shared drinks and food on the two previous evenings.

-Material from the Associated Press was used in this report