A 28-year-old Washington nurse who was on her way to meet her boyfriend in Ocean City, Md., was found strangled in a field Thursday, 40 miles from where her car had been discovered.

Police said yesterday they had few clues and no suspects in the death of Monica A. McNamara, 28, of Arlington, who worked at Children's Hospital in the District. McNamara's boyfriend, John O'Connell, 34, told police he discovered McNamara's 1976 Pinto along Rte. 90, eight miles west of Ocean City, as he was driving to work at an Eastern Shore hospital Thursday morning.

The keys were found six feet behind the car, which had no apparent mechanical defect, authorities said. An hour later, a man walking home from work found McNamara's fully clothed body near a canning factory just outside Pocomoke City. There were no signs of sexual abuse or struggle, authorities said. McNamara was missing a shoe and authorities said they cannot find her purse.

"We're looking for a good theory," said Somerset County prosecutor Logan Widdowson. "We just don't have a whole lot of answers."

McNamara's family, friends and colleagues also had no answers. She was described by her close friend, Mary Colaianni, as "wholesome, sensible and warm."

Colaianni said McNamara had been especially happy since she had begun dating O'Connell, a medical technician and former employe at Children's Hospital.

O'Connell told police he discovered McNamara's car at 6:45 a.m. Thursday, as he was driving to Peninsula General Hospital in Salisbury from Ocean City. The car was on the eastbound shoulder of the road.

O'Connell said he got out of his car, looked inside the Pinto, saw nothing and drove about three miles to a Maryland State Police station, where he reported finding the car and his girlfriend missing.

Colaianni, a former classmate of McNamara's at Georgetown University School of Nursing, said her friend didn't take chances or stop for hitch-hikers. "Nobody could believe she'd stop for anything," said Colaianni. "It had to be something very freakish. She'd never stop for a hitchhiker. I can't imagine her not fighting."

Only one "oddity" had occurred in McNamara's life in the last two months. Colaianni said. "She'd gotten some phone calls from a guy -- heavy breathing stuff -- and she didn't know who it was. He used her name, and that bothered her. She was thinking about having her phone number changed."

Colaianni said she last talked to her friend about 4 p.m. Wednesday.

She said McNamara planned to leave for Ocean City by 6 p.m. It was a route she had driven before, Colaianni said.

Police said O'Connell is a heart pump technician who works at different hospitals.When he works at Peninsula General Hospital in Salisbury, he stays in a condominium in nearby Ocean City, Colaianni said. McNamara had visited him there once before, she said.

McNamara had called her parents in Monroe, Conn., Wednesday afternoon to tell them she planned to spend the next few days at the beach, said her aunt, Mrs. Fred Ray.

McNamara, who had worked at Children's Hospital for the last six years, counseled children -- and their families -- in the ear-nose-and-throat department. Colaianni, a registered nurse, said she and McNamara had traveled to Toronto in May to present research they had done on home care teaching programs for the parents of children with throat problems.

"I've never seen her so happy as she was in the last two months," Colaianni said. "She was on a high, both personally and professionally.

"One of the doctors called me last night and said he was in surgery and the chief of surgery came in and said, 'Have you all heard about Monica McNamara?''' Colaianni said. "They hadn't, and he told them she'd been murdered. The doctor couldn't handle the case. He had to leave the operating room."

"She was an exceptional nurse," said McNamara's boss, Dr. Ken Grundsast. "'ll never be able to find a replacement for her."

McNamara had planned to return from Ocean City in time to have dinner with friends tonight, Colaianni said. She said they planned to go grocery shopping together Sunday and were looking forward to picnicking at the Judy Collins concert at Wolf Trap Farm Park Monday night.

"She was my best friend," Colaianni said. "How many people are there in the world who you can call up in the middle of the night and say, 'Come get me?' Monica was one of those. You could count on Monica for anything . . . Who knows what happened?"