A federal prison inmate in Pennsylvania has been sentenced to two dozen more years behind bars for killing his cellmate in what authorities say was a dispute over the death of a pet mouse.

Forty-three-year-old Tommy Meeks, of Frostproof, Fla., pleaded guilty a year ago to second-degree murder in the May 2004 death of Douglas Leonard. Both were serving terms for firearms crimes in the Allenwood federal penitentiary, about 60 miles north of Harrisburg.

Authorities say Meeks had been raising a pet mouse called Amadeus in his cell but found the animal dead and blamed his cellmate. Four days later, they say, he killed the Ohio construction worker with a rock brought in from the prison yard.

Meeks, who had expressed remorse, was sentenced Tuesday to 24 years, 4 months for the crime. His attorney raised a mental health issue, but U.S. District Judge John E. Jones III called the crime a "calculated act of violence."