To describe Sabina Rose O'Donnell as a familiar sight around Northern Liberties would be almost an understatement.

On most days, O'Donnell, 20, would ride her bike up and down Girard Avenue, or join a friend on a dog walk near the Piazza at Schmidts. The tellers at Hyperion Bank on Girard saw O'Donnell each week when she stopped by to cash her paycheck. Regular lunch and dinner customers of PYT in the Piazza always remembered her, as did the staff at the restaurants lining Second Street, who often saw her surrounded by friends.

"She was just incredibly popular," said party promoter Tommy Updegrove, owner of PYT, who hired O'Donnell when she was 17. "It's kind of amazing how many friends she had."

As police search for whoever killed O'Donnell near her apartment at Fourth Street and Girard Avenue late Tuesday, those friends have stepped forward from all corners of Northern Liberties.

They have joined her relatives and Northern Liberties business owners to post a $25,000 reward for information leading to the arrest and conviction of the killer. Anyone with information can leave tips anonymously at 215-546-8477.

O'Donnell's mother, Rachel, 41, visited her daughter's home and the nearby sidewalk memorial Thursday night and read aloud a brief statement.

"My daughter, Sabina Rose, was a beautiful, magical woman," she said. At least one TV station recorded the statement, and O'Donnell's mother asked it to share the tape with other media outlets because she did not want to be bothered any more by reporters.

O'Donnell's nude body was found Wednesday morning in a lot behind her apartment building. She had been beaten and strangled. Police do not believe she knew her attacker.

Updegrove, known as Tommy Up, has established a fund to raise money for funeral costs and to increase the reward.

"I'm just trying to round everybody up so we can give her a proper send-off," he said. "She was like our goofy little sister. Everybody wants to do what they can."

O'Donnell, who would have celebrated her 21st birthday this month, attended high school at the Franklin Learning Center and excelled in dance classes at local studios, her friend Phalla Sen said.

"She danced all her life," said Sen, who described O'Donnell as her best friend. "Everyone was always inspired when they saw her dance."

O'Donnell was a teenager when she met Sen, who was her hairdresser. Sen did O'Donnell's hair for the high school prom, then tried some new styles on her. She said she had come to think of O'Donnell as a younger sister.

"She's always had a pure heart. She never had anything bad to say about anyone," Sen said. "She was someone who didn't need much to be happy."

Sen introduced O'Donnell to Up, Sen's boyfriend. O'Donnell started working the door at Up's parties at 17, smiling and crossing names off guest lists.

When Up opened PYT last year, O'Donnell was one of the first people he hired.

"She was a hostess, but then she made some very compelling arguments to be a server," Up said and laughed. "We finally gave her the opportunity, and she did a great job."

But O'Donnell had aspirations beyond the food-service industry. She loved music and was starting to explore a possible career in fashion or photography. She modeled for a local clothing company, Fresh Melt Water design, and talked about starting a photo blog.

Though Northern Liberties has a core group of longtime residents, the neighborhood has in recent years undergone a transformation that has drawn large numbers of young people to live and work there. With its galleries, trendy hot spots, upscale shops, and blossoming bar scene, the area was the perfect fit for O'Donnell. She loved nothing more than to spend the night out and about with friends.

"We ran this neighborhood," Sen said and laughed. "She's a part of it."

Most recently, O'Donnell was living in an apartment with her stepfather just over the Northern Liberties border in North Philadelphia, a distinction O'Donnell most likely wasn't even aware of.

She spent Tuesday night out with friends, then went to a friend's apartment at Front Street and Girard Avenue. She left after midnight and headed the short distance home on the friend's bicycle. She left her cell phone at the friend's house by mistake, Sen said.

Police believe O'Donnell was approached by a man outside her home who dragged her to a lot on Orianna Street behind the building.

A neighbor found O'Donnell around 10 a.m. Wednesday. Shortly after 11 a.m., when O'Donnell was supposed to show up for work, Up learned that she was missing, and that a body had been found near her house.

Sen got a call Wednesday morning from O'Donnell's stepfather, who sometimes called her looking for his daughter when O'Donnell's phone was switched off.

"I'd always be like, 'Yeah, she's safe,' then I'd tell her to call him," Sen said. "This time when he called me, it was the first time I couldn't tell him that."

The crime shocked Northern Liberties residents, many of whom had come to think of the area as safe. O'Donnell's death has prompted neighbors to urge one another not to walk home alone at night.

"A lot of people feel like this is an idyllic place to live," said Up, who has lived in the neighborhood for 10 years. "So, for this to happen half a block outside of our 'safe zone' is unacceptable."

In addition to PYT, the Silk City Diner Bar & Lounge on Spring Garden Street is collecting donations for the Sabina Rose O'Donnell Fund. Fishtown's Kung Fu Necktie bar, where O'Donnell was a regular, planned to donate door proceeds from a party Thursday night to O'Donnell's family. Up will host a party at Octo on Saturday on the waterfront and will dedicate all proceeds to O'Donnell's family because, he said, she would have been there dancing all night.

To Sen, the hardest part is imagining the coming days without O'Donnell. The two talked constantly, she said, and almost every day O'Donnell joined Sen while Sen walked her dog.

"She was one of the only people who pronounced my name the right way," Sen said, her voice breaking. "And when someone said it wrong, she always corrected people. It sounds like a small thing, but it's what I keep thinking about."

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