Chicago police charge Raysean Comer, 16, as an adult in fatal shooting and killing of Jai'mani Amir Rivera, 7, on the Near West Side

CHICAGO (WLS) — A 16-year-old suspect appeared in court Saturday and was charged as an adult with first-degree murder in the shooting death of 7-year-old Jai'mani Amir Rivera earlier this week.

Rivera was shot and killed Tuesday on the West Side. Raysean Comer, 16, faces several criminal charges for first-degree murder and personally discharging a firearm causing death.

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Rivera's grieving family left court Saturday afternoon moments after a judge ordered Comer to remain behind bars.

“You took all the life out of my baby,” said the victim’s aunt, Vanessa Rivera. “My baby didn’t get to live his life.”

In court, prosecutors said Jai'mani was bringing a pot to a 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 justice for him,” said community activist Saleshea Peterson.

At the scene of the shooting, detectives recovered 13 shell casings in the parking lot of Crane High School, just yards from Oakley and Jackson.

Investigators said a 9-1-1 call, several anonymous tips, surveillance video showing Comer fleeing the scene, as well as information from two Chicago police officers familiar with Comer, led to the identification of the suspect thanks to a police report. All information pointed to the teenager, including a witness who said she was playing cards with Comer and others after the murder.

“Another person who was playing told the defendant that she would have nightmares about what he had done, referring to killing people,” said Cook County Deputy District Attorney Anne McCord . “In response, the defendant replied: 'I didn't mean to do that.'”

Comer was arrested at his home Thursday. Police recovered 13 shotgun shell casings at the scene, but were unable to find the weapon used in the shooting. They found a gun stolen during the arrest that was not used in Tuesday's shooting.

Authorities said the teen already had pending criminal charges for auto theft and aggravated robbery, and was served with an arrest warrant after cutting off his electronic monitoring bracelet .

Amid their immense grief, the family continues to advocate for an end to gun violence.

READ MORE | Teen charged with murder in shooting death of 7-year-old boy on Near West Side, Chicago police say

The charges were announced Friday by Chicago police.

Police said Comer, 16, is currently believed to be the only suspect involved in the shooting. The motive for the shooting is not known and police said he may not have been targeting anyone when he allegedly fired randomly and aimlessly with an assault rifle.

“We can't give you a motive for this offender's actions. I wish I could tell you more, but that's the frustration we feel here,” said Chief Antionette Ursitti.

Police said they believe Rivera was about 300 feet from the suspected shooter when he was struck by gunfire.

“It is absolutely infuriating and heartbreaking that innocent children are dying in our city,” said Chicago Police Superintendent Larry Snelling.

Comer is scheduled to appear in court again on Tuesday.