DES MOINES, Iowa — Authorities have confirmed that a body discovered in the Des Moines River on Friday is that of missing teen Kathlynn Shepard.

Shepard, 15, and a 12-year-old girl were abducted after they got in a stranger's vehicle at their school bus stop on May 20, police said. The man reportedly made them an offer to earn money for mowing grass.

The 12-year-old was later able to escape. The suspect, 42-year-old Michael J. Klunder, was found dead, classified as suicide by hanging.

But Shepard remained missing for nearly three weeks, despite an extensive search that scoured fields, a river and wooded areas over roughly 220 square miles. Investigators also released a school bus video surveillance image of Shepard exiting the bus shortly before she was abducted.

Then on Friday evening, Boone County 911 received a call of a possible body seen in a log jam in the Des Moines River near Boone. An autopsy was conducted on Saturday, and authorities announced on Sunday that the body was confirmed to be that of Shepard.

Dr. Julia Goodin, chief state medical examiner, determined the cause of death to be multiple sharp and blunt forced injuries. The death was ruled a homicide.