CHICAGO (CBS) — The victim of a sexual assault on the far North Side is speaking out, hoping to stop a predator.

It has been exactly one month since Alexandria Clarke walked to the bus stop at Devon and Clark.

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The 22-year-old Loyola University graduate says she’s speaking out now because she wants to do everything possible to catch her attacker.

“I was listening to music, I wasn’t really paying attention if someone sat next to me, it happens all the time,” said Clarke.

Clarke sat down, waiting for the Clark street bus at Devon when a 300-pound man sat next to her, and took her neck in his hands.

“He grabbed my throat a second time and said I was going to walk with him or he was going to kill me,” said Clarke.

The man walked Clarke one block south, past a cellphone shop that captured them on security camera, the man with his arm around her, then a half block east on Highland and into an alley where he sexually assaulted her.

It all happened around 2 in the afternoon and Clarke says pure fear kept her from screaming, or trying to escape.

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“He also told me not to make any noise or he would kill me, so I didn’t want to do something cause I could have gotten myself hurt or someone else hurt if I tried to get someone involved,” said Clarke.

Four days after the attack, police released a sketch of the assailant, and today Alexandria and her family announced a $5,000 reward for the suspect’s arrest. The Guardian Angels have joined Clarke at nearby Schreiber Park, teaching some self-defense moves to the public.

Guardian Angels demonstrate self-defense moves. (Credit: Michele Fiore)

Guardian Angels demonstrate self-defense moves. (Credit: Michele Fiore)

“I think that the offer of the reward might entice someone to bring forward any little piece of evidence that might help,” said Renee Touchton, the victim’s mother.

And Clarke says, it’s her mother who convinced her to speak out.

“I don’t care if people know. I’m not ashamed. A crime is a crime, just because it’s a sexually based crime doesn’t make it any different,” said Clarke.

Clarke says her assailant never displayed a gun, but she couldn’t be sure he didn’t have one.

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And she said, he was so sure of what he was doing, where he was going, and so bold about his actions in broad daylight, she’s sure he’s attacked other women before.