A 67-year-old Arlington woman was fatally beaten by an assailant who attacked her Sunday night in the underground garage of her Pentagon City apartment building, police said yesterday.

Police spokesman Tom Bell said Jean C. Velie, who lived in River House 1 at 1400 S. Joyce St., was found about 7:40 p.m. Sunday by several residents of the building. She was pronounced dead at 9:23 p.m. in Arlington Hospital.

Bell said an autopsy conducted yesterday afternoon indicated Velie died of wounds to the head.

The woman was alive but unconscious when found on the first level of the River House underground garage, in her assigned parking space, Bell said. Her car, a green 1970 Pontiac GTO convertible, was missing, he said.

Police found the car yesterday afternoon, parked near the 14th Street bridge, about a mile from the River House apartments.

No weapon was found in the garage, and the autopsy showed "no indication that an object was used," to strike Velie, Bell said.

"At this point, we don't know what the motive is; this is a puzzler," he said. "No one saw anybody suspicious in the garage."

Tenants are required to punch a code into locks to gain access to the garage, he said.

"Maybe she came down to get something from her car and found someone stealing it -- we don't know," Bell said.

Bell said residents of the building described Velie as a lively woman, "younger than her years," who particularly cherished her car, considered a classic model.