The St. Paul Pioneer Press reports DA Dan Steffen characterized the death of Isaiah Theis as "a perfect storm that led to a real tragic ending." No charges will be filed because there was no evidence of intent or recklessness.
The boy's body was found last July in the trunk of a car on his family's property in the northwestern part of the state, near the Minnesota border. The discovery was made by the car's owner nearly 27 hours after Isaiah was last seen playing with his brother in their home. The cause of death was probable hyperthermia.
About 2,500 people participated in an extensive search for the boy, but the car was not checked because authorities didn't believe he would be able to unlock the doors and climb in on his own.
Steffen said numerous forensic tests and a re-creation of events were conducted until authorities determined Isaiah's death was accidental. The investigation found the boy, whose father was a mechanic, used the car keys to open the trunk.
The family's pastor said at the time that Isaiah's father worked on cars on the property and the family believed the boy had taken the keys from his father's shop.
"He spent a lot of time with dad in the shop, and if he saw you do something once, he could repeat it easily," the Rev. Rick Van Gundy said.
In his statement, Steffen said the sheriff's office has "gone above and beyond with providing me as complete a picture as possible as to what happened."