Lacking direct physical evidence and relying largely on the word of an admitted liar, the criminal case against the alleged ringleader in arsons that ravaged a subdivision under construction in Southern Maryland "just fell apart," a defense attorney argued shortly before jurors began deliberations Thursday.

Prosecutors countered that defendant Patrick S. Walsh's remarks to friends and investigators showed that he planned the fires at Hunters Brooke, a predominantly black, upscale subdivision in Indian Head, about 30 miles south of Washington. They urged jurors to believe the testimony of Jeremy D. Parady, who pleaded guilty to a felony in April and, in exchange for leniency, testified as a prosecution witness at Walsh's trial.

Walsh, 21, is one of six men who were charged with damaging or destroying two dozen unoccupied houses in various stages of completion at the Charles County development before dawn Dec. 6.

Two of the suspects -- Parady and Aaron L. Speed, a former security guard with the company hired to protect the development -- have pleaded guilty. Charges against another, Michael E. Gilbert, were dropped.

The case against Walsh is the first to go to trial. Jurors in federal court in Baltimore deliberated for five hours yesterday but did not reach a verdict. Walsh is charged with conspiracy and numerous counts of arson.

Jury deliberations resume Friday.