Witnesses saw a man in a heated argument with a woman at about the time she was beaten bloody in Central Park and left unconscious, police said.
The unidentified woman, who appears to be in her 20s, was in critical condition Thursday."Somewhere out there, there is somebody who knows her, somebody who is missing her," Police Commissioner Howard Safir said.
Besides reports of an argument, some witnesses heard screaming before seeing the man flee. Police were preparing a sketch of the suspect, who they believe knew the victim, said one investigator who requested anonymity.
But police officials cautioned that the information collected so far was vague, and they appealed to the public for more help.
"We feel there are a number of witnesses out there who can not only identify the victim but describe what happened," Deputy Inspector Wayne Bax said.
A woman walking her dog found the victim bleeding and unconscious Tuesday afternoon steps away from a playground and across the street from pricey Upper West Side apartments.
She had severe head injuries, apparently inflicted by a blunt object. Investigators also found "indication of a sexual attack, but she was not in fact raped," Safir said.
Iris Fass, who found the woman, told The New York Times that the woman's clothing was in disarray.