When the young man ended his late-night shift at Starbucks at Fourth and South Streets in South Philadelphia and headed home, he likely was listening to comedy through earphones that plugged into the iPod classic he kept in his front pocket, authorities said.

That, Clark said, may be why Zabel was targeted.

Zabel was fatally shot about 1:30 a.m. yesterday when he was ambushed as he walked to his apartment from the coffee shop. He was shot once in the neck in the 800 block of Ellsworth Street and fell to the sidewalk, police said.

He was pronounced dead at the scene.

When homicide detectives arrived, the iPod he was always known to carry to listen to comedy was missing and the pocket where he normally carried it had been turned inside out, Clark said.

Detectives think that may be why he was targeted since Zabel still had his backpack with his wallet and money. Clark said the robbery had gone bad and it appears the gunman, and possibly one other person, were quick to flee after the shooting.

Authorities said they have reviewed surveillance tapes of nearby businesses where Zabel is seen on his way home, but there are no recordings of the shooting. Clark said Zabel may have been followed by two people, but detectives are still reviewing the tapes.

Anyone with information is asked to call homicide detectives at 215-686-3334, 3335, or 3336.

Zabel's mother, Lana Zamora, said by telephone yesterday from Austin, Minn. that she was heading to Philadelphia today.

"I thought I had to worry about him in the classroom, not on the streets," Zamora said.

Zamora said that she had driven her son here on May 2 and was assured by his new roommate that the neighborhood was safe. Now she is filled with disbelief and regret.

"Beau decided what he wanted to do," she said. "I raised my children to make their own decisions."

The second of three children, Zabel appeared to be a young man of great promise.

An Eagle Scout, he grew up in the small city of Austin near the Iowa border, where Hormel makes meat products and the city proudly proclaims itself "Spam Town USA." He graduated in 2007 from Augustana College, a liberal arts school in Rock Island, Ill., where he studied mathematics, Spanish, philosophy and computer science.

"He was a really good student," said Thomas Bengston, chairman of the Augustana math department, who described Zabel as good-natured and easy-going. "Things didn't get him down."

Zabel was attracted to teaching, but he did not have a degree in education. He was drawn to the Philadelphia Teaching Fellows program because he could teach in city public schools while getting his certification through Drexel University.

Zabel chose Philadelphia over a similar program in Chicago so he could be near an aunt who lives in Lancaster, Pa., Zamora said. He planned to have dinner on Friday with his cousin, she said.

On Ellsworth Street yesterday, neighborhood youths played basketball just a few feet from where the young man fell, oblivious to the stained sidewalk. Neighbors expressed shock that a violent crime had occurred on their quiet block, though some grumbled about the recent influx of immigrants as a signal that the neighborhood was changing.

Deena Burgase said she was wakened by the shot and immediately dismissed it as a problem with the utility lines - the electrical equipment had popped off recently. It was only after police arrived that Burgase understood that a young man had been killed across the narrow street from her rowhouse.

"I thought it was a transformer explosion," she said. "This is the first shooting in our neighborhood."

Zabel was the city's 139th homicide this year, compared with 181 by this time last year.

Zabel's mother got the word yesterday and was eager for any news. "We don't have a whole lot of murders up here," she said.

She was numbed by the news. She works as a victim's advocate for a nonprofit organization but did not fully comprehend victimization until yesterday.

"I've worked with a lot of victims," she said. "It's different - a way different feeling - when you're the victim. I thought I would be angry, but right now I don't care what happens to the people who did this.

"It won't bring my son back."

Contact staff writer Barbara Boyer at 215-854-2641 or bboyer@phillynews.com.