A hunter discovered the bodies about 25 miles north of Evansdale, Iowa, where Lyric Cook-Morrissey and Elizabeth Collins have not been seen since they went on a bicycle ride July 13. Their bikes were found near Meyers Lake, but an extensive search through the countryside and examination of car trunks and seats found no sign of them.
"We have no one else missing in this area, two bodies were found, and the bodies were smaller in stature," Black Hawk County Sheriff's Capt. Rick Abben said Thursday.
Abben did not indicate how long the bodies might have been in the park and did not say what the cause of death might have been, The Des Moines Register reported.
He declined to discuss possible suspect, the newspaper said.
He said the families of Lyric Cook-Morrissey and Elizabeth Collins were told of the discovery.
"It's definitely not the outcome that we wanted, obviously," Abben said.
Lyric was 10 and her cousin 8 at the time of their disappearance
A reward for information in the case grew to $150,000 recently when an anonymous donor added $100,000.
Jordana Brewster on Paul Walker: 'He was an enormous presence in my life'
Couple mistakenly served bag of cash at McDonald's drive-thru