Rivera was shot and killed by a stray bullet Tuesday on the West Side. Raysean Comer, 16, is facing multiple felony charges for first-degree murder and for personally discharging a firearm that caused death.
The grief-stricken family of Rivera left court Saturday afternoon moments after a judge ordered Comer to remain behind bars.
"You took my baby's whole life away," the victim's aunt, Vanessa Rivera, said. "My baby didn't get to live his life."
In court, prosecutors said Jai'mani was taking a cooking pot to a next-door neighbor at the Oakley Square Apartment Complex for his mother when shots rang out. A security camera captured the boy's movements minutes after he was shot in the back. He was rushed to a nearby hospital where he later died.
"The only thing that matters to them is Jai' Mani, and that justice will be served for him," community activist Saleshea Peterson said.
At the scene of the shooting, detectives recovered 13-shell casings in the parking lot of Crane High School, just a few feet away from Oakley and Jackson.
Investigators said a 9-1-1 caller, several anonymous tips, surveillance video showing Comer run away from the scene, along with information from two Chicago police officers familiar with Comer, helped identified the suspect through a police bulletin. All information pointed to the teen, including a witness who said she was playing cards with Comer and others after the slaying.
"Another person who was playing told the defendant he will have nightmares about what he did, referring to killing people," Cook County Assitant State's Attorney Anne McCord said. "In response, the defendant said, 'I didn't mean to do that.'"
Comer was arrested at his home on Thursday. Police recovered 13 rifle casings on scene but have not been able to find the weapon used in the shooting. They found a stolen weapon during the arrest that was not used in Tuesday's shooting.
Authorities said the teen already had pending criminal cases for allegedly stealing a car and aggravated robbery, and he had a warrant issued for his arrest after he cut off his electronic monitoring anklet.
Amid their enormous grief, the family is still pleading for the gun violence to end.
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The charges were announced Friday by the Chicago Police Department.
Police said the 16-year-old Comer is believed to be the only suspect in the shooting at this time. A motive for the shooting was not known, and police said he may not have been targeting anyone when he allegedly fired an assault-style rifle randomly and aimlessly.
"We cannot give you a motive for this offender's actions. I wish I could tell you more, but this is the frustration that we feel up here," said Chief Antionette Ursitti.
Police said they believe Rivera was about 300 feet away from the alleged shooter when he was struck by gunfire.
"It's absolutely maddening, heartbreaking that innocent children are dying in our city," Chicago Police Superintendent Larry Snelling said.
Comer is schedule to appear in court again on Tuesday.