UPDATED 10/24/11 7:19 a.m.

CHICAGO (CBS) — One moment, Harry Rodriguez of the Belmont-Cragin neighborhood was celebrating his birthday.

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The next, he lay dying after being shot in the chest at his own party. He was just about to turn 24 on Wednesday.

As CBS 2’s Dana Kozlov reports, Rodriguez was with more than a dozen friends in an apartment in the two-flat where he lived in the 2000 block of North LeClaire Avenue around 1:55 a.m. Sunday, when a gunman burst in and opened fire.

Rodriguez and another man, 21, suffered gunshot wounds to the chest, police said. They were both taken to Advocate Illinois Masonic Medical Center, where Rodriguez was pronounced dead, police said. The 21-year-old was listed in critical condition, according to police.

Rodriguez’s mother, Elizabeth Ramirez, wanted to talk with CBS 2 Sunday night, and tell the story of how wonderful her son was. She said he was a high school graduate taking college classes, and would do anything to help anyone.

What Ramirez couldn’t say is why the masked man burst into the back door of the apartment and started shooting. Police are still working on trying to answer that question too.

“I want my son back!” Ramirez sobbed with raw pain.

She was inconsolable.

“The one that killed my son – please give yourself up,” she said. “He didn’t do anything to you.”

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Ramirez is adamant that her son, who was also known as Deejay, was never involved with any criminal activity.

“My son was into sports. He had a life. He didn’t need to be in a gang,” Ramirez said.

The dozens of people comforting Ramirez Sunday echoed that statement, and say no one at the party was a gang member. In fact, they described Rodriguez as a caring man who was taking college classes to become a physical education teacher.

“He was a hard-working kid – always into sports, helping young children to get out of the streets,” said Nancy Berrios, Rodriguez’s aunt.

No one has been able to explain why someone struck Rodriguez with five shots.

“Everybody that was at the party was good friends or a relative,” she said.

But Rodriguez’s family has one possible theory – that gang members from the block might have thought members of another gang were having a party in the two-flat.

Police will only say they are investigating, and no one is in custody.

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The Sun-Times Media Wire contributed to this report.