A 37-year-old man who was arrested Thursday on charges of public drunkenness died yesterday morning in Fairfax Hospital, hours after he was discovered unconscious in the Fairfax County jail, officials said.

Sheriff M. Wayne Huggins, who operates the jail, said the death of John R. Thompson of 1401 Trap Rd., Vienna, illustrates why the facility should not be used as a "dumping ground for drunks.

"Had there been in existence a central detoxification center where persons like Mr. Thompson could be taken for alcohol-related offenses, better care and treatment could be initiated for persons with this problem," the sheriff said.

Thompson was found unconscious on the floor of his cell at 6:15 a.m. Thursday, about four hours after he was jailed, Huggins said. Medics were unable to revive Thompson and he died at 2:30 a.m. following surgery to remove a blood clot on his brain, the sheriff said.

Officials said they have not determined what caused the blood clot and Huggins said doctors found no indications of external injuries to the body. "It would have happened no matter where this person was," the sheriff said.

Thompson, arrested at 1:20 a.m. Thursday on misdemeanor charges of public drunkenness, following a citizen complaint, was placed in a cellblock dayroom used as a holding area for incoming prisoners because of space problems in the jail, Huggins said. Other prisoners in the cell, which has no beds, told deputies that Thompson lay down on the floor and apparently went to sleep.

Deaths in the county jail were a frequent topic of controversy in the late 1970s and the county police department is investigating the latest death, Huggins said. Commonwealth's Attorney Robert F. Horan Jr. said yesterday there appears to be no evidence of improper actions by jail officials in connection with the latest incident.

Huggins said Thompson had "apparently suffered from alcoholism for a number of years."