Per your link:
Prosecutors said Friday the girls were found “badly decomposed.” Police previously said the girls were believed to have been buried for “some time” before they were discovered.
I'm trying to make sense of that. The dog walker that lived directly across the street said his dog would sniff that spot. After about 'a week' he finally decided to dig it out and take a look. It's winter in Cleveland. Not like it's summer so decomp would be fast, it would be slower in lower temps. So, if the dog hit on that spot about a week before... it's likely (in my uneducated on the subject opinion) that it was fairly newly buried.
Is 1 week in winter temps enough to make their bodies "badly decomposed"? I ask because they might have been dead longer than a week. I posted upthread where a neighbor mentioned not seeing them play outside over the summer, and she even put up a bouncy house.