ROAD TOWN, British Virgin Islands — If a judge agrees with everything defense lawyers said during five days of legal arguments, four Americans charged with killing 34-year-old Lois McMillen could walk out of a courtroom here as free men on Thursday.

But he could decide that there is enough evidence to warrant the sensational trial, the longest criminal proceeding in the history of this British territory, to go the distance.

High Court Justice Kenneth Benjamin told the nine-member jury hearing the murder case that there would be no court Wednesday. The seven women and two men on the panel have been relegated to a back room at Eastern Caribbean Supreme Court for a week were told only that lawyers were involved in an "exercise."

The trial has moved laboriously along in recent days as defense lawyers and prosecutors continued to argue whether enough evidence was presented through 24 prosecution witnesses to sustain murder convictions beyond a reasonable doubt. Benjamin said Tuesday he will rule on that and other issues Thursday at 10 a.m.

The prosecution says it presented ample evidence to prove that William Labrador, Michael Spicer, Alexander Benedetto and Evan George killed McMillen, a former model from an affluent Connecticut family, by drowning her in shallow water along the shore of Sir Francis Drake Channel last year.

But even if Benjamin concludes that there is insufficient evidence that some or all of the defendants committed the murder, prosecutors say the jury can legally return verdicts on lesser charges of accessory to murder after the fact.

The opinion, made after defense lawyers had concluded their motions to dismiss arguments last week, brought a rebuke from Benjamin and protests from the defense that their clients were being ambushed. They pointed out that Senior Counsel Theodore Guerra told Benjamin, when the judge asked at the start of the trial April 2, that the prosecution was proceeding only on the indictment for murder.

Although the judge said even he was surprised by the maneuver, prosecutors said their "learned friends" on the defense must have known about a law that says juries can always deliberate guilt or innocence on charges not included in indictments if evidence to support them are presented.

The defendants, who all pleaded not guilty Oct. 3, have been held without bail since Jan. 15, 2000, the day McMillen's fully clothed body was found laying face up on the south coast of the island of Tortola, one of more than 50 volcanic outcroppings that make up the British Virgin Islands.

Labrador, 37, is a former talent and model agency executive from New York City and Southampton, N.Y. His childhood friend, 35-year-old Alexander Benedetto of New York, dated McMillen for several months in 1997. Both Labrador and Benedetto were staying at the vacation home here belonging to the family of Michael Spicer of Charlottesville, Va., a 37-year-old law school graduate who knew McMillen for about 20 years. George, 23, lives in a Washington, D.C., apartment owned by Spicer.

The defense argued for a week since the prosecution rested that with no physical evidence to link the men to McMillen or the crime scene on the night she was killed, it would be wrong legally for Benjamin to let the jury return verdicts. The lawyers said that it would be a travesty of justice if convictions were based solely on the testimony of a prison informant who testified that Labrador confessed.

The informant, convicted swindler Jeffrey Plante of Texas, told the jury that Labrador admitted drowning McMilllen after a heated argument over money. Neither Plante nor the prosecution elaborated on the alleged motive and no evidence was offered to the jury to explain the alleged roles of the other defendants in the killing.

Regardless of whether the defense or prosecution believes the testimony of Plante, the prosecution maintains, the jury heard about the alleged confession and should be allowed to deliberate.

An expert testified during the month-old trial that 15 percent of .2 grams of sand found in one of Spicer's sneakers probably came from the same shoreline where the body was found. Because Benedetto and George claimed they were with Spicer throughout the evening when McMillen was killed, the prosecution argues that by extension the evidence puts them at the crime scene too.

Benedetto's attorney, Paul Dennis, called the reasoning ludicrous while replying Tuesday to the prosecution's objection to his motion to dismiss. Dennis' reply was actually longer than his original motion. He repeated again and again Tuesday that there is no evidence for the jury to deliberate and his opinion that Benjamin has a duty to stop the trial before an injustice is committed.

Benjamin, who choose his words carefully, asked the lawyer for Spicer and George, Joseph Archibald, how the trial might proceed if he threw out the murder charges and let the jury consider accessory after the fact.

Archibald, a distinguished lawyer with 41 years experience, said the prosecution gave up its right to seek convictions of the lesser offense when they told Benjamin that they would only try to prove the charges of murder when the trial began.

If Benjamin forced the defense to answer the charges of accessory to murder after the fact, Archibald said the defense could insist that prosecution witnesses be brought back for further cross-examination.