A suspect in the fatal stabbing of a U.S. Environmental Protection Agency employe in her Crystal City office Friday night was found in a restroom where the victim's credit cards had been thrown in a toilet, Arlington police said yesterday.

Homicide Detective Michael B. Hill said a District teen-ager, whose identity is being withheld, was being held in the slaying.

Hill said an intruder was chased by a building guard who received a telephone call from a second woman on the 11th floor "who was screaming." The guard lost sight of the intruder after the guard stopped to pick up a pair of scissors believed to be the weapon in the slaying, Hill said.

Police later sealed off the building and began a search. Hill said the suspect was found in a women's restroom. Money amounting to less than $50, apparently taken from the victim, was recovered.

The woman, Linda M. Billings, 45, director of the farm safety staff in EPA's office of pesticide programs, died at 9:15 p.m. at National Orthopaedic & Rehabilitation Hospital in Arlington, about three hours after the attack. Hill said Billings, who lived in Cabin John, received multiple stab wounds in the chest and side.

Hill said a 16-year-old is to appear in juvenile court tomorrow, when authorities are expected to ask that he be charged as an adult in the slaying.

A GS-15 who worked for the EPA for seven of the 15 years she has lived in the area, Billings was described by friends as highly dedicated and hard working, a person who often stayed late in her 11th-floor office at Crystal Mall 2 at 1921 Jefferson Davis Hwy.

According to Hill, the assailant allegedly encountered Billings in her office about 6:30 p.m. Friday and stabbed her in the course of a robbery. "It appears there was a small struggle," Hill said. "It doesn't look like there was an out-and-out fight."

The officer said Billings' purse and wallet were left in the office.

The suspect is a Southeast Washington resident who is believed to be a high school dropout.

The assailant probably entered the office building through the Crystal Arcade, an underground shopping mall, before 6 p.m., Hill said, noting that unrestricted elevator service is cut off to upper floors of the office building at 6 o'clock.

Shortly after Billings was stabbed, Hill said, a building guard was alerted by a telephone call from another woman on the 11th floor. The guard rushed to the floor, where he saw a youth fleeing Billings' office, Hill said.

The guard chased the youth down the stairs but stopped to pick up the scissors when they were dropped, Hill said. Billings apparently managed to take the elevator to the first floor before collapsing, he said.

When a second guard told police no one had left, the building was sealed and searched. "The only way out of the building at that hour is through the security area, so we knew he was still in the building," Hill said.