The teen, whose name has not been released, allegedly posted photos of the dead kittens on Facebook Aug. 3, the Northwest Indiana Times reported.
"The photos are really disturbing," Lake County police Detective Michelle Dvorscak said Wednesday. "I've been investigating animal cruelty for the county for about 12 years and this is the first time I've seen this. Who knows how often it takes place. He was just stupid enough to post it."
Police were alerted to the photos by several anonymous phone calls, Dvorscak said.
The photos, one of which showed a kitten speared through the head and another disemboweled, have been removed from Facebook because of their objectionable nature, Dvorscak said.
The teen has been interviewed and said he hunted the kittens because he was bored.
"The guardian said this is the first time he has been in trouble," Dvorscak said.