The man accused of firing the shot that killed Aiden, 25-year-old Marcus Anthony Eriz, is currently being held without bail.
Wynne Lee, 23, who is charged as an accomplice in the shooting that killed Aiden, was released on electronic monitoring a few weeks after she and Eriz were arrested by the California Highway Patrol on June 6.
Aiden was killed May 21 while his mother was driving him to kindergarten. The boy was sitting in the passenger booster seat when someone in another vehicle opened fire on the 55 Freeway.
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The boy was rushed to Children's Hospital of Orange County, where he was pronounced dead.
Investigators said the couple allegedly became involved in a confrontation with Aiden's mother, Joanna Cloonan, on the freeway.
Prosecutors allege that Eriz was riding in a car driven by Lee and fired the shot after the traffic confrontation. Both had pleaded not guilty in June.
The arrests of Eriz and Lee ended an intense manhunt from authorities.
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Eriz has been charged with one felony count of murder, one felony count of shooting into an occupied vehicle, and one felony enhancements of the personal discharge of a firearm causing great bodily injury and death, according to the Orange County District Attorney's Office. He faces a maximum sentence of 40 years to life in state prison if convicted on all counts.
Lee has been charged with one felony count of accessory after the fact and one misdemeanor count of having a concealed firearm in a vehicle. She faces a maximum sentence of three years in state prison and one year in the Orange County Jail if convicted on all charges.
Lee and Eriz are scheduled to be arraigned April 12 in Santa Ana.