The grainy video, which you can watch above or clickhere, was shown to the media on Thursday afternoon. The video shows the man police want to talk to.
"We think he was on the prowl looking for a victim," Captain James Clark of the Philadelphia Police said.
The person of interest is described as a young black male, medium build and height.
He is wearing a white tank top and is seen riding a bicycle through the area where O'Donnell was attacked. He passes by the camera several times but, at one point, (not seen in the above video), a person who resembles O'Donnell rides a bicycle by and the man stops his bike, turns around, and follows her.
"When you see her ride by on the bike and then you see this individual turn around and go after her. That is the final minutes before this crime takes place," Clark said.
Police say the white tank top the young man is wearing matches one found at the crime scene. They also say he likely lives in the neighborhood and someone knows who he is.
Anyone with information on this man's identity can call the Citizen's Crime Commission at 215-546-TIPS or the Philadelphia Police at 215-686-TIPS. The Crime Commission is offering a $25,000 reward for information leading to an arrest and conviction of a suspect.
O'Donnell, 20, was found dead on Wednesday, June 2nd in a lot next to the apartment building where she lived with her stepfather in the Kensington section of Philadelphia, near the border of Northern Liberties.
Police say O'Donnell died of strangulation and was sexually assaulted. Her body was found nude with a bra wrapped around her neck. Police are testing DNA samples found on her body in hopes of finding a suspect.
Police say O'Donnell was out with friends the night of Tuesday, June 1st at El Camino, a bar on 2nd Street, and ended up at a friend's house at Front and Girard. At some point early on June 2nd, police say O'Donnell rode a bicycle home.
Police say an unknown male snatched her as she arrived at her apartment building and she was then dragged to the rear of the building.
Sabina's friends and relatives created a Facebook page in her memory which featured many photos of a young woman described by her mother as a beautiful, magical woman.
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At Liberty Lands Park Thursday afternoon, hundreds gathered for a memorial service.
Friends say the service was to celebrate, not mourn, Sabina's life, because she wouldn't want it any other way.
Sabina's mother and stepfather addressed the large crowd.
"Both Rachel and I are aware of how hard the officers have all been working and words are not sufficient to express our gratitude," stepfather Mark Rounds said.
"People keep telling us that Sabina is in a better place, I know any place that has Sabina in it is a better place," mother Rachel O'Donnell said.
