Lawyers are seeking freedom for a college student sentenced to 30 years in prison in a 1980 drug deal in Virginia, alleging that state officials failed to disclose that an informant in the case was a fugitive from justice and a second informant was a habitual criminal who was being shielded from prosecution by a state police officer.

The attorneys have stated in court papers that the fugitive remains at large and that the second informant has been placed on probation despite felony convictions on drug and gun charges.

The two lawyers' client, Robert W. "Rusty" Gibson, 27, of Fredericksburg, has spent the past 16 months in a Virginia prison.

"I feel like he was railroaded," says Gibson's mother, Betty Jo Gibson, a Fredericksburg real estate agent. "I think the whole system's unfair. The big men never go in to prison . It's always the little man."

Gibson's lawyers, John K. Zwerling and Michael S. Lieberman of Alexandria, do not dispute prosecutors' charges that Gibson, then a student at East Tennessee State University, had been involved in an effort in Southwest Virginia to sell a pound of cocaine. But they contend that Gibson's role was minor compared to the part played by the informants who were protected.

"It doesn't outrage state officials in Richmond," says Zwerling. "They're doing nothing about it."

Jay Cochran, director of the state police Bureau of Criminal Investigation, declined to comment on the case.

"The Gibson matter is in the courts," Cochran said, "and we do not comment on informants." He would only say, without elaborating, that state police officers involved in drug enforcement operations all receive special training.

Federal prosecutor Thomas J. Bondurant Jr. feels that one of the informants in the case was not being properly controlled by the police who were dealing with him.

"The guy Lee Roy Dunford was running wild, in my opinion," says Boudurant, an assistant U.S. attorney in Roanoke who handled federal drug and gun charges against Dunford there. "It went on and on and on and somebody had to stop him. He ran around saying: 'I am the law, I am the law.' "

Zwerling and Lieberman--who last summer won a reduction of Gibson's sentence to 20 years on the ground that it was excessive for a first-time offender--also have charged in court papers that a Bristol, Va., attorney hired by Gibson's mother failed to take dozens of routine legal steps that might have lessened her son's sentence or possibly helped acquit him of the charge.

Bristol Circuit Court Judge Charles Flannagan II is expected to rule soon on the request for Gibson's release, which is opposed by the Virginia Attorney General's office. Virginia officials have argued that Gibson's conviction and sentence should stand because both conformed to state law.

Among the allegations by Gibson's attorneys:

* That one informant, identified in prosecution testimony as "Bennie Leonard," actually was Dunford, a Southwest Virginia drug dealer. Dunford allegedly avoided prosecution by informing on others under a controversial plea agreement that gave him immunity for his offenses while on the state police payroll.

* That the second informant, identified in court as "Ronald Rash," was in fact William Wright, a dangerous, convicted felon who was wanted by police and who had pressured Gibson into helping to arrange the sale of a pound of cocaine for $28,000 to a Virginia undercover agent;

* That the agent, Virginia State Police officer James E. Asbury, testified he did not know the informants' true identities or whereabouts when, in fact, he was in daily contact with Dunford and personally had arrested Wright on a felony charge a year earlier.

* That Asbury on several occasions intervened with other police officers to help Dunford and even to get charges against Dunford dropped. These allegedly included a charge of attempted murder filed after Dunford shot his girlfriend's husband, and a similar charge lodged when Dunford allegedly shot a bystander outside a Las Vegas casino.

* That Asbury lacked the authority to endorse the plea agreement that set Dunford up as a drug informant and that he gave Dunford, a convicted felon, permission to carry a gun in violation of Virginia State Police policy.

* In the Nevada shooting, the two lawyers say, Asbury traveled out-of-state to argue successfully to local authorities that Dunford was a valuable Virginia state police informant who should not be prosecuted. Asbury has testified that the trip was paid for by Dunford's lawyer, Gilbert Davis of McLean.

"I'm sure Lee Roy paid for it directly, or it was paid through my firm," Davis said this week. "I wanted Asbury to go, not to carry a brief for Dunford but to establish as a credible fact that he was working for the Virginia state police."

State police confirm that Asbury still is on the force, but decline further comment.

Dunford was indicted on 11 counts and was permitted to plead guilty to only three counts. He was placed on probation for five years. Prosecutor Bondurant says that federal authorities were reluctant to interfere in state affairs.

"It wasn't the best thing I ever had in court," Bondurant says of the federal plea ageement.

Attorneys Zwerling and Lieberman have acknowledged in court papers that "Rusty" Gibson was a "recreational" user of marijuana and cocaine while he was a student at East Tennessee State University, across the Virginia border from Bristol.

Gibson agreed to introduce Wright to an alleged cocaine dealer because Wright was a "dangerous and very unpredictable person" who often showed up armed at Gibson's house, according to the lawyers.

The transaction took place at about 1:30 in the morning on April 15, 1980, in a Bristol motel room, according to court records. Of five men present--Gibson, Dunford, Wright, Asbury and the dealer, James M. Mounce--only Gibson was unarmed, his lawyers say. They contend that Gibson witnessed the sale, but never possessed the cocaine and did not play an active role. Gibson "was just there," Asbury testified later.

At most, says Zwerling, Gibson should have been charged with helping set up the drug deal, called an "accommodation" sale under Virginia law, rather than possession of cocaine with intent to distribute it. An accommodation sale is punishable by up to 10 years in prison in Virginia.

Zwerling and Lieberman say that Gibson received no money in the transaction.

If all fails, the lawyers say, Gibson, now incarcerated at St. Bride's prison in Chesapeake, Va., will have to serve about one-fifth of his 20-year sentence.