A 13-year-old dog was found beaten to death at a home in the Miami area with a handwritten note taped to it that read: "WE BEAT IT 2 Death lol! :) HAHAHA!," police said on Tuesday.
The Pomeranian was found at the back of a home in the small south-east Florida city of Pembroke Pines, police said in a statement.
Although officers saw no visible injuries on the dog, the police statement said, a veterinarian at the Saint Francis Animal Hospital determined the canine suffered multiple bone fractures "consistent with blunt force trauma."
The Pembroke Pines Police Department said the dog-beating appeared to be an isolated incident and there was no evidence to suggest other animals in the area were in danger.
Police said they had opened an investigation of animal cruelty.
The South Florida Sun-Sentinel newspaper reported that the dog, named Foxx, scampered down the stairs of the family's condo on Friday evening to relieve itself on the lawn behind their building, but did not return.
"I called for him and I didn't hear anything," Verline Barthelemy, who shares the condo with her boyfriend Ronald Boisvert, told the newspaper.
"He'd always come back."
On Saturday morning, a neighbour discovered Foxx's red-hued 3kg body on a stair leading to the patio and alerted Boisvert, the newspaper reported Barthelemy as saying.
"I'm hoping that after the first hit, he was already gone and didn't feel what came next," she told the newspaper.