A congressional aide, testing whether security had been increased as promised in a Crystal City office building where an employe was killed, said yesterday that he had easily evaded guards in the building and then had to wait 25 minutes for them to respond to his calls.

"I was trying to duplicate what I thought an employe in distress would be doing," John Galloway, staff director of the House subcommittee on government activities and transportation, said of his Monday night experiment.

He said his test was requested by Rep. Cardiss Collins (D-Ill.), subcommittee chairwoman, in the wake of the Nov. 29 robbery and fatal stabbing of Linda M. Billings, an Environmental Protection Agency official.

Billings, 45, was stabbed about 6:30 p.m. while working in her 11th-floor office in the Crystal Mall 2 building at 1921 Jefferson Davis Hwy. Police arrested a 16-year-old District youth who was found in a rest room.

The slaying, Galloway said, drew Collins' concern because her subcommittee has jurisdiction over the General Services Administration, which leases the building and is responsible for the safety of 1,300 federal employes there.

Collins fired off a letter Tuesday to GSA Administrator Terence C. Golden complaining about "significant flaws" in the agency's security system and GSA's "misleading" assurances about increased security after the slaying. She said her subcommittee would be forwarding to Golden recommendations for improved safety measures.

The building where Billings was killed is guarded by the Baltimore-based Echelon Security Services under a contract with GSA. Echelon's guards were on duty the night Billings was killed and on Monday during Galloway's test.

Under the new security measures, anyone entering the building after 4:30 p.m. must show identification to guards in the lobby. Elevators from the underground shopping mall and parking levels also are set to stop there after 4:30 p.m.

At 11 p.m. Monday, Galloway said, he took an elevator from the garage to the lobby where neither he nor the guards could see each other because of the location of their desk and because they were monitoring the front door. He then walked down the hall away from them and up to the third floor, where he took an elevator to the office where Billings was killed.

Once there, Galloway said, he telephoned the guards' desk in the lobby but got a busy signal for more than five minutes. He then called the Federal Protective Service, the GSA's security arm, but was told to call another number. Two calls later and 25 minutes after he made the first call, two guards responded from the lobby, he said.

"I told them who I was and said I wanted someone to come up immediately with an explanation of how I got there," Galloway said.

He said that subsequent interviews with the guards showed they had been unsuccessful in their requests to make what Galloway called "common sense" changes, such as adding a second telephone line at the guards' desk and relocating it to give them a better view of both the elevators and front door.

In her letter, Collins criticized the GSA for blaming the guards, who she said were "highly motivated and responsible." She also asked that the number of guards be increased so some could stay on duty while others checked the building.

GSA spokesman Dale Bruce said yesterday that the agency "appreciates that she has called this breach of security to our attention and has tested our security because the safety of federal employes is our No. 1 mission."