Company security guards looking for shoplifters at Hecht's department store in Prince George's Plaza spied on customers in dressing rooms via an assortment of holes, vents and displaced ceiling panels, according to three former security guards who said they participated in the practice while working there from 1980-82.

Some holes and vents above dressing rooms at the store were covered in April after inquiries from a reporter.

Hecht Co. officials deny that dressing-room spying, which is a violation of company policy, is permitted or takes place in their stores.

Such activity used to be common in retailing but has been abandoned in the last 15 years largely because of concern over invasion of privacy issues.

"Let me tell you that it is an absolute violation of Hecht Co. policy for there to be a violation of dressing rooms," Edgar S. Mangiafico, Hecht's chairman of the board, said in an interview a month ago. "If there is ever any indication that that has occurred in any way, shape or form, the people involved are summarily dismissed."

He said that the Hecht Co. has dismissed employes on two occasions for spying into dressing rooms and that periodic outside inspections by Hecht officials ensure that security at the stores is conducted according to company policy. Mangiafico declined to say who the employes were or when they had been dismissed.

The three guards, who worked on and off at the Hyattsville store, said that surreptitious surveillance of men's and women's dressing rooms by male guards perched at observation posts called "booths" was an extremely effective but publicly unacknowledged method for catching shoplifters and diminished the risk of false arrest while they served on the security force.

According to the former guards, paperwork completed after an arrest would often report that accused shoplifters had been observed leaving dressing rooms with fewer items than they had entered with. In many of those cases, however, the decision to detain a shoplifter was based on direct observation of dressing rooms by guards in hidden positions.

Last year, the number of shoplifters caught at Hecht's in the Prince George's mall more than doubled, to 170, from the previous year. This year, as of late last month, 55 people had been arrested for shoplifting there; 32 in March alone.

"There's been a tremendous increase in caseload," said Bruce Eddy, the present security supervisor for the Hyattsville store, adding that he has never lost a shoplifting prosecution. The guards said the store was near the top among Hecht's 23 area stores in terms of number of arrests and merchandise recovered.

The surveillance, the former guards said, was conducted with the knowledge of security supervisors. One former guard said he was once told by a former supervisor to watch a suspected female shoplifter from a booth above the juniors' department dressing room. However, Eddy and one former security supervisor at the Hyattsville store said they did not know of or approve any such activity.

The three former guards said they had used covert observation booths with views into four fitting rooms up to last Christmas. Guards would normally wait until they suspected someone of shoplifting before going up into the booths, but some guards "camped out" and watched the dressing rooms until they caught someone, the guards said.

"When I first started at the store, I was shown the booths," said Dana Narode, a recent University of Maryland graduate and former security guard. "The main point of the booths were if you saw somebody suspicious, you would go up to the booths and watch them. . . . We wouldn't make an arrest unless we'd seen them stealing."

"The use of these booths was totally without hesitation," said Stephen Silverfarb, who worked as a security guard at the store from February to August last year. He now works in security for another retailer. "It wasn't a question of filling out a form or asking a supervisor. I'm the last person to stick up for shoplifters, but people have rights."

A third guard, who asked that his name be withheld because he is still technically "on call" at the store, said he also participated in the surveillance.

In Maryland, prosecutors say no law specifically forbids spying on dressing rooms by security guards. In the District, a decision by the Court of Appeals said security guards were not bound by 4th Amendment guarantees against unreasonable search and seizure that govern police officers.

To reduce the expectation of privacy in dressing rooms, where the majority of thefts occur, some stores have trimmed the length of the door or curtain that screens the dressing room so that it extends only from the shoulders to the knees of the customer. Other stores have posted signs advising customers that the fitting room area may be under surveillance.