Donte Johnson had been in police custody for just a few hours when he started talking, a Philadelphia homicide detective told jurors Friday. Before investigators collected a DNA sample from him, the 18-year-old from North Philadelphia confessed to raping and strangling Sabina Rose O'Donnell in a lot on the edge of Northern Liberties.

When detectives showed him a photo of a man on a bike — an image taken from surveillance footage near the crime scene on June 2, 2010, when O'Donnell was slain — Johnson said: "That's me." He then wrote "Me" under the image, Philadelphia Detective Thorsten Lucke said.

The jury was dismissed for the day before Johnson's attorneys began cross-examining Lucke, but in the past the lawyers have challenged the statement Johnson made to police, saying Johnson has mental disabilities that would have prevented him from understanding his rights. They also have suggested that the language used in the confession was more sophisticated than Johnson's verbal skills would have allowed.

Johnson faces life in prison if convicted in the death of O'Donnell, who was a few weeks from turning 21 when she died. O'Donnell's family and friends have attended each day of the four-day trial, as have Johnson's mother, siblings, and other relatives.

Lucke, one of two homicide detectives with experience recovering video surveillance, testified that for weeks after the killing, police combed through cameras in the blocks near the crime scene, searching for possible suspects. They spotted the man on the bike, Lucke said, kept tracking his location through other cameras, and eventually discovered footage of him crossing paths with O'Donnell. Soon after police released the still photograph of the man to the media, someone called in a tip with Johnson's name.

Lucke narrated a series of surveillance videos presented to the jury, depicting Johnson as he biked up and down Girard Avenue between 2 and 3 a.m. on the day O'Donnell died. Before Johnson saw O'Donnell, he was filmed following another woman on a bike for several blocks, Lucke said.

The final moment of footage played for jurors led O'Donnell's mother, Rachel, to put her head in her arms and sob quietly. Just before 3 a.m., a camera at Fourth Street and Girard captured O'Donnell as she biked to her home, a half-block away. Seconds after O'Donnell crosses the screen in a blur, Johnson, who had been biking in the other direction, turns around and follows her.

Jurors also heard testimony from Michelle Lipson, who lived on the second floor of O'Donnell's apartment building. Johnson told police that after he killed O'Donnell, he took her keys and entered her building. He found himself in Lipson's apartment and went to the bathroom to wash his hands.

Lipson had fallen asleep on her couch and awoke to hear noises. She saw her apartment door closing and ran down the hall to see who it was, she said. When she got downstairs and opened her front door, she saw a shirtless young man bending down over a bicycle on the street. He also was carrying a purse that was later identified as O'Donnell's, she said.

Contact Allison Steele at 215-854-2641 or, or follow on Twitter @AESteele.