For the second time in two weeks, a major figure in a Washington area massage parlor described by the FBI as a Major prostitution ring has unexpectedly pleaded guilty to interstate racketeering and agreed to tell prosecutors all he knows about the alleged $1 million a year operation.

Officials described the guilty plea yesterday of Gary Marion Van Ryzin, 38, as another indication that their 18-month investigation into the activities of massage parlor entrepreneur Louis Michael Parrish is at the "steamroller" stage.

"Things are really moving now.

We're getting calls from people we're interested in, people we've been looking at. We may have something really big within the next few weeks," said one senior official, declining to elaborate.

Van Ryzin was so well regarded and highly placed within the Parrish operation that he was permitted to handle cash, something the secretive Parrish, who always carried a 357-magnum revolver, permitted very few people to do, officials said.

Additionally, one source said, the fact that Van Ryzin is not mentioned in the detailed, 33-page affidavit that U.S. officials filed in court last May in order to procure a search warrant is an indication that the investigation has progressed well beyond its original scope.

Federal official said yesterday additional guilty pleas are expected in connections with allegations of inter-officials.

U.S. Attorney William B. Cummings presented the case against Van Ryzin at 2 p.m. in U.S. District Court Judge Albert V. Bryans nearly empty courtroom. Van Ryzin, whose hair had been uncombed and shoulder-length several weeks ago when he escorted a woman friend to the grand jury investigating Parrish's activities, sat quietly at the defense table yesterday his hair neatly trimmed.

Cumminhs said that on April 26 Van Ryzin had taken an undisclosed amount of cash from the Foxy Lady Outcall Massage Service, 1001 Connecticut Ave. NW and deposited it at a United-Virginia Bank branch in Alexandria. The money represented the proceeds from "prostituting . . . and pandering," Cummings said.

Van Ryzin told Bryan in a loud and clear voice that the specifics of the charge were true and that he was guilty of them. "Yes, sir," he repeatedly said as Bryant asked him if he understood the nature of the charges against him.

Van Ryzin was told by Bryan that he faced a maximum of five years in the federal penitentiary and a $10,000 fine. The judge set Oct. 27 for sentencing. Van Ryzin was released on $1,000 personal recognizance bond.

Two weeks ago federal officials obtained their first guilty plea in the investigation, which began as a look at prostitution activities in the District of Columbia and quickly spread to Virginia. Clyde Ballard (Skip) Stovall Jr., 32, pleady guilty to a similar racketeering count in which he also acknowledged taking money from the Foxy Lady service to the Alexandria bank. He will be sentenced Oct. 13.

Stovall and Van Ryzin are both represented by attorneys Lawrence Schwartz and William Jordan Temple, who also represent Dawn L. Peck, described in the FBI affidavit as manager of the Foxy Lady Outcall Massage Service. Two weeks ago Peck testified before the U.S. grand jury investigating Parrish's activities. The grand jury is expected to resume work in one month and to return indictments within several months, according to federal officials.

Assistant U.S. attorneys Henry Hudson, who has presented all the evidence to the grand jury, and Paul Murphy, who has been directing the prosecution's investigation into arrish's parlors in the District of Columbia, were present in the courtroom yesterday. FBI agent Charles Bartles III, who wrote the affidavit that detailed the alleged interconnected nature of all of Parrish's activities, sat in the audience.