Police are searching for information about the vicious murder of a 21-year-old woman who was found naked this morning in a vacant lot in Northern Liberties.

Sabina Rose O'Donnell, who lived with her stepfather on the 1200 block of N. 4th Street, was found by a neighbor walking a dog shortly before 10 a.m., said Philadelphia Capt. Jim Clark. No official cause of death has been determined, but there were signs of blunt force trauma to her face and body, Clark said. She apparently also was strangled.

Her body was in a vacant lot off North Orianna Street, behind the building where she lived, with items from her purse strewn around nearby.

O'Donnell, who worked at a nearby restaurant, was out with friends at two bars on 2nd Street in Northern Liberties last night, Clark said. Around 10 p.m. she went to her friend's apartment, near Front Street and Girard Avenue. She was last seen around midnight when she asked to borrow her friend's bicycle and pedaled home, a distance of a few blocks.

Police believe her attacker was a stranger who approached her as she tried to enter her home, and that he dragged her behind the building. Police are asking anyone who heard or saw anything to call the homicide division at 215-686-3334.

Contact staff writer Allison Steele at 215-854-2641 or asteele@phillynews.com