Authorities in Polk County, Wis. are trying to determine how 2-year-old Isaiah Theis got into the trunk of a locked car not too far from his home in rural Centuria.

Isaiah's body was discovered in the trunk of a Chevrolet Impala around 10:15 p.m. Wednesday, Polk County Chief Deputy Steve Moe said at a news conference Thursday. The car belonged to a customer at a nearby repair shop.

Moe didn't elaborate on the investigation or give any hints on what lead up to the boys's death. The Polk County Medical Examiner's Office is conducting an autopsy to determine the cause of death.

A search party of hundreds of volunteers and law enforcement was launched after Isaiah was reported missing Tuesday evening. Isaiah's parents told police their son was last seen playing with his 7-year-old brother and must have wandered off, something Isaiah has been known to do in the past.

For several hours over the course of two days, searchers scoured a 2-square-mile area with no luck until the owner of the Impala returned with the keys and found Isaiah's body.

A vigil is being held in Centuria Thursday night.