Quovadus Mahomes, 17, of Dixon, was charged with murder and two counts of attempted murder, police said. View Full Caption Chicago Police Department

COOK COUNTY CRIMINAL COURTHOUSE — A man in a police interrogation room to be questioned about a murder was caught on video urinating on his hands to wash away gunshot residue, prosecutors alleged Thursday.

Quovadus Mahomes, 17, allegedly rubbed urine on his hands to beat the evidence test, prosecutors said.

Mahomes, of Dixon, appeared in Bond Court Thursday, charged with the murder he was being questioned about — this week's shooting of Devin Common.

Common, a 27-year-old Park Manor man, lost his younger brother to gun violence in 2011. Their mother, Kimberly Common, said Devin helped her grieve his brother's murder. Now, she's lost two sons to Chicago violence in just two years.

Common was one of three people shot dead in Chicago Tuesday. The others were 15-year-old Hadiya Pendleton and 20-year-old Gino Agnotti.

Common's alleged killer, Mahomes, is also charged with attempted murder in the shooting of two other people Tuesday, when he allegedly opened fired in the middle of the day. Those two survived their wounds.

According to prosecutors, after his arrest, Mahomes was told that gunshot residue tests would be performed. He was caught a short time later on camera urinating on his hands and clothing and "wiping his hands on his urine-soaked clothing in an obvious attempt to thwart the GSR testing," Cook County Assistant State's Attorney Jamie Santini said.

Jeffrey Granich, Mahomes' private attorney, balked: "My client's response was that he had to pee."

"I find it hard to believe that [Mahomes] would be that familiar with forensic evidence and ballistics testing ... After 20 years of doing murder cases, I've never heard of [that]," Granich said.

Cook County Judge Donald Panarese Jr. ordered Mahomes, already on probation for a 2011 burglary, held without bail.

Common was found dead in the 7400 block of South Champlain Avenue after he and two other men were shot about 12:15 p.m., police said. The block is in Park Manor, part of Greater Grand Crossing.

His mother, Kimberly Common, said she didn't know about Thursday's hearing until late in the morning.

But when she heard about it at 10 a.m., she said she wanted to be there.

"I really want to see this boy's face," Kimberly Common said, her cheeks stained with tears. She said she wants to see her son's murderer get life in prison but hopes she can one day forgive him.

Kimberly Common sat with family and friends in the living room of her Grand Crossing home Thursday, still asking why her son was taken from her. He was the second of her four children to be gunned down on the streets of Chicago in less than two years.

Kimberly Common said before the shooting her son told her he was walking down to the store at 75th Street and Langley Avenue to get a cup of coffee, something she said her son did every day.

A man came to her house shortly after her son left and told her about the shooting.

"He said, 'These three, they just gunned Devin down,' " Kimberly Common said. "And I ran down the street, calling out God's name."

She got close enough to see that it was her son's body on the ground. It was too much for Kimberly Common, who said she was still grieving from the death of her first son, Antonio Common, who was also shot and killed just blocks from their home in October of 2011.

Kimberly Common's living room is still decorated with tributes and pictures of Antonio. She said after that murder, she tried reaching out to city officials for help.

"I had tried the year before last to reach out to the mayor, the alderman. I didn't get no response from nobody," Kimberly Common said, adding her recently-slain son Devin also tried.

"Devin grieved for his little brother," Kimberly Common said. "He talked about him a lot."

Her son Devin also tried to ease his mother's grief. The day before his death, Devin Common threw his mother a surprise birthday party, she said.

Family and friends remember Devin Common, a father of five, as a funny person who liked to keep people smiling. His girlfriend, Diane Trice, said he was a "family man" who loved being with his kids.

"He loved video games, basketball, dancing," Trice said. "He loved to see people smile."

Kimberly Common said she when she viewed her second slain son's body at the morgue, it did not look like Devin.

"My son didn't look like himself at all," Common said. "It was like some type of light was in his eyes."

She said standing there, looking at the second son she has lost, she felt fed up with the violence in Chicago.

"And I remember saying right there, 'When is this going to stop? 'Who is going to do something about this gun violence?'"

Contributing: Darryl Holliday