Updated 08/20/12 – 5:58 p.m.

ST. LOUIS (CBS) — A $10,000 reward is being offered for information leading to the arrest of the gunman who shot and killed a former volleyball player from Wheaton, who was gunned down in her car in St. Louis over the weekend.

Megan Boken, 23, was killed Saturday afternoon while sitting in her car in the Central West End neighborhood of St. Louis. A $10,000 reward is being offered by the Central West End Neighborhood Security Initiative for information leading to a suspect’s arrest.

A 2011 SLU graduate, Boken was in St. Louis for a reunion game for former volleyball players, scheduled to take place about two hours after she was killed. When she didn’t show up, her teammates knew something was wrong.

Authorities initially said there were conflicting reports about the gunman, and that it was possible Boken knew her attacker. But, on Monday, St. Louis Police spokesman David Marzullo said there was no evidence she knew the gunman, and detectives were investigating the case as a probable attempted robbery.

LISTEN: WBBM Newsradio’s Steve Miller reports

The gunman has been described as a black male, with a medium complexion, and a thin build. He is 5’8″ to 5’10”, with short hair, and was last seen wearing a grey charcoal shirt, khaki pants, and white tennis shoes.

Boken’s teammate Sarah Entzeroth said, “There is no way she knew this person. No way. Not possible. We don’t hang out with people that have guns, or that carry guns, or that hurt people. No one that knew Megan Boken would ever hurt her.”

Boken had been planning to move back to St. Louis from the Chicago area, where she and Entzeroth were planning to be roommates.

“She’s my best friend, and she is one of the greatest people I’ve ever met,” Entzeroth said.

On Monday, Boken’s father, Entzeroth, and Boken’s other former teammates did what loved ones do at a time like this – they shared memories and offered each other comfort.

Paul Boken said, for his daughter, “it was all about SLU volleyball. It was everything to her. She was coming back to play with her friends. These people are very special to her.”

He said he is now thinking of how everyone who loved his daughter can pay a lasting tribute.

“Megan is a big person to miss, but we’re a strong family. … Megan’s our example. We’re going to do things for Megan now,” he said.

Meantime, investigators have been processing Megan Boken’s car for evidence and have been canvassing the area around the shooting for any surveillance video that might assist in the investigation.

Boken graduated from St. Louis University in 2011, and had moved back to Wheaton, but was back in St. Louis on Saturday for an alumni volleyball game.

Word of Boken’s murder in broad daylight in St. Louis had those who knew her wondering why anyone would kill her.

“Just a real tragedy. Her family, it’s just hard to even fathom that she’s gone,” said Boken’s former gym teacher, Bill Cashin. “She was a very good student. She was a very good athlete. But best of all, she was just a real good kid. You know, nice to everybody.”

Former teammate Amelia Karges said Boken had just finished having lunch with a friend in St. Louis’ Central West End neighborhood when she was shot in or near her car, just before 2:30 p.m. on Saturday.

“They went their separate ways to walk to their cars, and Megan was on the phone with her mom when she got cut off. … This wasn’t somebody that she knew,” Karges said. “I think that’s why it’s so, so painful, is because this was so senseless. I mean, nobody – nobody – could ever have a motive against this girl. There was nothing not to love about her.”

A graduate of St. Francis High School in Wheaton, Boken was in her white Volkswagen in St. Louis’ Central West End neighborhood at about 2:15 p.m. Saturday, when she was shot in the neck and chest.

The gunman fled the scene on foot. So far, police have no leads in the case.

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