Two weeks ago a 19-year-old Northern Virginia youth stood nervously before the white-haired judge and heard him announce in a thunderous voice something the youth was not likely to forget

"This man faces 240 years in the penitentiary.He may never see the light of day again," said Prince William Circuit Court Judge Percy Thornton.

With that warning Thornton revoked Garland Kino Gaskins' bond and ordered him held for sentencing next month for committing 12 burglaries in the suburban county.

The judge's statement has had another impact: It transformed the tall, slender youth into a symbol for angry Prince William County blacks who charge that Gaskins and others have become victims of a double standard of justice -- one under which blacks in the county regularily receive stiffer sentences than whites.

"When I heard about this I wanted to retailiate on my own," said Juanita Johnson of Gainesville, a member of a Prince William NAACP committee that is looking into the Gaskins case. "We are living within a stone's throw of the nation's capital. Is anybody's stereo set worth 240 years?"

More than 200 people gathered at Gainesville's Mt. Pleasant Baptist Church on Monday as Johnson and other black leaders expressed their dismay at Thorton's statement.

Many spoke of the death, three years ago this month, of 16-year-old Charlotte Diane Mason killed by a bottle thrown from a car carrying three white juvenile males who had been out drinking that night. All three youths received suspended jail terms for manslaughter although they originally had been charged with first-degree murder, according to court records.

Charlotte's father, 50-year-old Leroy Mason, a former Fort Belvoir plumber whose eyesight is damaged by diabetes, expressed the anger of many at the meeting Monday.

"These white boys got no time at all for killing my daughter," Mason's voice shook. "People get stiffer penalties for littering. Now they want to give this boy 240 years for burglary. It just isn't fair."

Prince William's chief prosecutor, Paul B. Ebert, said in an interview yesterday that critics of the judge are premature. Haskins "has not been sentenced yet" Ebert said. "I'd be very surprised, if he received a 240-year sentence.

Under Virginia law each of the 12 burglary counts carries a maximum penalty of 20 years in prison.

"There is no indication of more hars h penalties for blacks than for whites," Ebert said. "The Mason case was not an intentional killing. One kid was throwing a bottle at a building and unfortunately she was in the way."

The people who gathered Monday night plan a protest at the county courthouse in Manassas for Gaskins' sentencing Aug. 22. They have received a promise from Frank Tyler, a conciliation specialist with the U.S. Justice Department's community relations service, to look into Gaskin's case.

Gaskins was one of 12 men and three juveniles arrested Jan. 12 in a raid in Manassas' Georgetown South section, a raid that Prince William County police said involved "one of the major burglary rings in the county . . . and closed over 40 unsolved cases."

Gaskins' convictions were his first as an adult, his mother said in an interview. Her son was convicted in 1977 for the theft of a citizen band radio and was tried as a juvenile, she said.

His conviction was gained on the statements of George Washington Cherry of Manassas, a member of the theft ring who was granted immunity from prosecution in return for his testimony, according to court records.

Prosecutor Edward Fox called on a number of victims who had been burglarized in 1979 and 1980 in the Missouri Place, Lake Ridge, and Georgetown South areas of Prince William County. Most of the thefts involved stereos, television sets, and jewelry, according to their testimony.

Gaskins' court appointed attorney, Peter William Steketee, repeatedly called Cherry's testimony questionable, but Thornton disagreed.

"He's (Cherry) a thief and I realize that," Thornton said. "But sometimes it takes a skunk to catch a skunk."

At Monday's meeting, Gaskins' mother Helen Jackson, read a letter from Gaskins that said, "I feel the sentence is unreasonable . . . a person committing murder could not receive a sentence like this."

"I'm a sick woman, but I came here tonight," said an angry Barbara Holmes of Manassas. "I'm hurting inside because I'm a mother, too. You could kill several people and not get a 240-yar sentence."

A secretary yesterday said that Judge Thornton was in conference in his court chambers and could not be reached for comment. But prosecutor Ebert said that there are "many examples to the converse" where whites actually have received stiffer penalties.

"I'm a great believer in communication," Ebert said. "I would be happy to sit down with these people and talk to them."

Neither side in the dispute was able yesterday to cite any specific Prince William statistics on sentencing to buttress its arguments. The issue of disparities in sentencing long has been a major political issue in Virginia, with State Attorney General J. Marshall Coleman and other arguing that blacks traditionally have received longer prison sentences than whites for identical crimes.

The state legislature repeatedly has rejected Coleman's arjuments for new laws that would restrict the lee-way state juges have in sentencing criminals.

Ebert also speculated that Thornton simply may have wished to impress the severity of the crimes on Gaskins when he mentioned the 240-year sentence. t"The court may not send him to prison at all," Ebert said.

Still, many of those who gathered on Monday night were prepared to attend the sentencing in force.

"If it is 110 degrees on sentencing day," said one man at the protest meeting, "don't look for no shade tree. Get up and march around that courthouse."