A federal grand jury in Alexandria yesterday indicted two more persons in its two-year-long probe of prostitution and interstate racketeering in the Washington area.

Debra J. Hernandez and Carlton Eugene Gentry Jr. were charged in connection with the string of massage parlors and outcall prostitution services run by convicted massage parlor operator Louis Michael Parrish. If convicted of all charges in the four-count indictment, Hernandez and Genry (also known as Carl Taylor) each face up to 20 years in prison and a $30,000 fine.

Plato Cacheris, an attorney who has represented them in the past, said Hernandez and Gentry would plead innocent at their arraignment, which is tentatively scheduled for Friday.Hernandez and Gentry could not be reached for comment.

Federal prosecutors previously won the indictment and conviction of Parish, Larry J. Wadino and Kathy Lynn Caldwell in connection with the once-flourishing massage parlor business, which officials estimated grossed more than $1 million annually. Prosecutors also have obtained guilty pleas from five others in connection with the Alexandria-based prostitution ring.

Sources have said during the past few months that once the grand jury finished its investigation of the Parish-owned massage parlors, it would try to determine why prostitution was able to flourish for so long in Alexandria when officials elsewhere in Northern Virginia were able to shut it down. U.S. Attorney William B. Cummings declined comment yesterday, except to note that the grand jury "has not been dismissed."

Hernandez and Gentry each were charged with two counts of travel in aid of racketeering, and two counts of transporting women across state lines for prostitution.

The indictment alleges that Hernandez and Gentry helped organize and run on behalf of Parrish two telephone outcall services known as "Dial Us" and "The Foxy Lady." The two facilities "offered outcall prostitution and related homosexual and heterosexual services to customers located in the District of Columbia, and states of Maryland and Virginia," the indictment states.

Hernandez and Gentry had printed cards and literature promoting the prostitution services, and Gentry designed advertisments for the massage parlors that were printed in the classified section of the Chesapeake & Potomac telephone directory, according to the indictment.