Jamari Cook, 17, from Kenosha is now facing several charges in connection with the Olivia Mackay case.
Cook is facing charges of Hiding a Corpse and Operating a Motor Vehicle without Owner's Consent.
CBS 58 News is not naming the second suspect in the case because he has not been charged yet.
According to the criminal complaint, Cook told police that a second suspect liked to meet girls online. That suspect allegedly arranged to meet up with the victim, Olivia Mackay, on July 23rd.
Warning: Graphic Details Included
According to Cook, the three of them went down by the lake. Cook then said that the suspect and Mackay appeared to be hugging so he gave them some space. When he looked again, he allegedly saw the suspect choking Mackay until she became motionless. The suspect then allegedly held the victim face down in the water for what seemed like 5 minutes. After that, Cook saw the suspect strangle the victim with an apron.
According to the criminal complaint, the suspect then asked Cook for help lifting her body into the trunk. Cook said that he helped because he figured "There was no going back now."
The suspect and Cook allegedly put the body of Mackay into her own trunk and drove to Racine county where they found an area with weeds and bushes.
The two then fled the scene and Cook asked the suspect what he would do with her car. He told the defendant he was going to "flip it" to get money.
Detectives with the Kenosha Police Department were able to track down a Facebook Messenger conversation where the suspect was trying to sell Mackay's vehicle.
The victim's body was found on July 24th by a couple who was riding around the perimeter of their property. Investigators were able to identify the victim as Olivia Mackay.
Cook will appear in court on August 15th for his Preliminary Hearing.
Stay with CBS 58 News for more information as this story develops.