A Georgetown University woman student was severely beaten and killed yesterday while working alone in an elegant Wisconsin Avenue clothing store as Saturday shoppers crowded the streets outside.

The victim was identified as Maureen A. McGrath, 18, of Mamaroneck, N.Y., a first-year student in the school of foreign service.

Her body, partially crammed inside a utility closet, was found about 1 p.m. inside Regent Place, a men's clothing store at 1641 Wisconsin Ave., where she reportedly had worked part-time for about two months.

Police began an intensive investigation which included stopping and searching buses on the busy street outside the store. They said last night they knew of no motive for the killing.

Investigators said they are trying to locate a man reportedly seen running from the stylish shop just before the body was found.

A witness told of seeing a man inside the store who placed a dark scarf over his head, then left with a plastic bag and vanished near Q Street.

According to detectives, an area businessman hailed a police officer shortly afterward and the two entered the store, which is on the ground level of a three-story detached brick rowhouse.

Police said the woman's legs were protruding from the closet, which is behind a counter at the rear of the 30-by-15-foot shop.

The woman's clothes were in disarray and spattered with blood, investigators reported.

It appeared, they said, that she had been severely beaten. However, a top homicide investigator said the cause of death had not been determined.

He said the victim may have been beaten to death, but it also is possible that she had been strangled.

An autopsy was reported scheduled for today to determine the precise cause of death.

In explaining that they had not found a motive, police noted that money was found in the store that likely would have been taken if the assailant had been a robber.

It was not clear whether any merchandise had been taken.

Police said there were no immediate indications that the woman had been sexually assaulted.

A friend at Harbin Hall, the slain girl's dormitory, told a reporter last night that the victim had been concerned about a man who at least once had appeared in front of the store and taken pictures through the window.

The student said that the same man had appeared in front of the store yesterday and that the slain woman had been worried and had planned to walk home after work with a friend employed nearby.

The account could not be confirmed immediately by authorities.

One area businessman said the owner of the clothing store, who was not identified immediately, had expected to be away from the store early yesterday and had planned to leave the key with a neighboring merchant so McGrath could open the store.

The businessman added that he believed the key was never left, but McGrath was able to open the store.

She apparently was the only employe there at the time she was killed.

Police sources said her purse, still containing her wallet, was found in the store.

A few hours later, passersby on Wisconsin Avenue found few signs of disarray behind the store's rectangular show window, with its display of shirts and a broad-lapel belted coat.

Inside the store a few hangers lay on the floor and a couple of scarves were draped casually over shirts.

McGrath graduated last June from the School of the Holy Child in Rye, N. Y., not far from her home town of Mamaroneck in Westchester County, just north of New York City.

Fellow students recalled the victim as an enthusiastic, lively, active woman.

"She was really joyful," one said.

She was described by friends as being interested in travel and as a field hockey enthusiast.

One student at the university where McGrath lived on the ninth floor of Harbin Hall said, "Everybody up there is really upset. Everybody around here has taken off. They've gone to Virginia or Maryland or anywhere just to get out of here."

A small group of students close to the slain woman locked themselves into the university's Office of Residence Life.

'They are devastated," said one school official. "The kids are just beside themselves and they're having trouble dealing with this."

Police said they are seeking a black man about 25 years old, 5 feet 9, about 170 pounds, with a medium build, medium complexion, wearing a three-piece light gray suit, and with a well-groomed bush haircut. They said he may have been the last person in the store with the victim and they asked anyone with information about him to call the homicide unit.