Charles Woodson, 41, of Front Royal, Va., purchased the guinea pig from a pet store, a criminal complaint said, and neighbors later witnessed him "wearing the skin of a guinea pig on his head," The Northern Virginia Daily reported Wednesday.
As officers answering the complaint approached Woodson's apartment March 1, he walked out wearing the skin on his head, the newspaper said.
Authorities say the animal cruelty crime took place on or about Feb. 1.
Among those testifying at Woodson's trial was the pet store employee who said she sold the guinea pig to Woodson, the newspaper said.
No date for sentencing has been set.