A body discovered Thursday night near a recreation trail was identified as April Millsap, Armada Police Chief Howard Smith said.
April's dog, which had stayed with the body, caught the attention of joggers using the Macomb Orchard Trail, about 35 miles north of Detroit. The body was 15-20 feet away.
The dog "kept coming up to them and going back into the woods," said Lt. Michael Shaw, a state police spokesman.
A cause of death was not disclosed. Investigators were looking for a gray van that had dents and was occupied by two males.
April took her dog for a walk after 5:30 p.m. Thursday. Her parents became concerned when she was still gone 90 minutes later.
Armada schools Superintendent Mike Musary said she would have entered high school in September.