Tyler Hayes Weinman was arrested Sunday after police searched his mother's house in Cutler Bay, where the killings began in April, The Miami Herald reported Monday.
Weinman's parents are divorced and he divided his time between his mother's home and his father's home in Palmetto Bay, the other community where the killings occurred, police said.
Weinman, known locally as an animal lover, belonged to the Facebook group "Catch the Cat Killer" and professed disgust about the killings in postings on his Facebook and MySpace pages, police said.
Police have not said what about the writings made them suspicious. The teenager's lawyer, David Macey, said his client is innocent.
Police allege Weinman sliced open cats' bellies, gutted them and often threw their carcasses onto the front lawns of their owners.
"Thankfully, for this community, the terror has come to an end," said Katy Sorenson, a Miami-Dade commissioner.