An 18-year-old Arlington woman pleaded guilty yesterday to first-degree murder in the slaying of Edith M. Miller, a county dry cleaning store owner who was stabbed 53 times in the face, neck, abdomen and back by her former employe during an apparent robbery attempt April 14.

Patricia J. Mawyer of the 2000 block of North Madison Street entered the guilty plea during a 10-minute session in Arlington Circuit Court. Judge Thomas R. Monroe set her sentencing for Jan. 27, at which time she could receive a sentence of 20 years to life.

Mawyer, dressed in a lilac sweater and black pants and carrying a large wad of tissues, listened calmly as Commonwealth's Attorney Henry Hudson outlined the state's case, which was tied to a bloody fingerprint that forensic tests showed was left by Mawyer on a snack tray at the store, the Old Dominion Dry Cleaning shop at 4036 Lee Hwy. Mawyer had worked briefly at the store last winter.

As Hudson described the case, Mawyer's apparent motive was to raise bail to get her boyfriend out of the Fairfax County jail.

But because of the 58-year-old victim's erratic bookkeeping procedures, which included many cash transactions, police were unable to establish if any money was taken. A red bank bag that an employe said was in the store when she left work the night of the murder could not be found the next day, Hudson said. He added that the store's regular accountant also reported that there were "several hundred dollars unaccounted for."

Nearly $1,600 in cash and checks were found untouched in the store when another employe arrived for work the next morning and discovered the body "laying in a large pool of blood behind the counter," Hudson said.

According to witnesses who worked in the neighborhood, Hudson said, Mawyer was seen outside the dry cleaning shop around 7:20 the night of the murder.

She was "peering in the window and appeared to be startled and dazed," and left quickly when she noticed the witnesses, Hudson said.

Later that night, he said, Mawyer called a Fairfax County bondsman to say "she now had the money to make the bond payment." She had previously tried unsuccessfully to get the money from a bus driver, Hudson said.

When Mawyer was arrested four days after the murder, she told police she had been in the store around 7:30 the night of the killing, but that Miller appeared to be "in fine shape and there was no blood around."