The family of Eli Hart identified him as the victim following the arrest of two people during the stop and police said it is being investigated as a domestic incident.
Police have not named the suspects, but the youngster’s mother, Julissa Thaler, was arrested on Friday and is currently in custody on suspicion of murder, showed Hennepin County Sheriff’s jail roster.
Court documents from Dakota County court showed Ms Thaler, 28, was awarded full custody of her son earlier this month, despite concerns social workers had about her mental health and criminal history, according to CBS-affiliated channel WCCO.
Orono police department officials said they were called out on Friday morning after reports of a car driving on a rim, with a smashed back window.
When they stopped the car, officers noticed blood inside the vehicle before finding the dead youngster in the trunk.
Police said they arrested the female driver of the car, while another person was arrested at an apartment complex.
Prosecutors have not officially confirmed the identities of those arrested. “It sort of shocks you, and our hearts go out to the victim in this as well as the officers, first responders,” said Orono Police Chief Correy Farniok.
“It is horrifying and difficult to process a tragedy of this magnitude, especially in our close-knit community,” Westonka Public Schools Superintendent Kevin Borg said.
“My thoughts and prayers go out to all those who are grieving this profound loss.”