Prosecutors at the court martial of an Army dog handler said Tuesday he was part of a crew of corrupt soldiers who enjoyed tormenting detainees at Abu Ghraib prison in Iraq.

Maj. Matthew Miller said in his opening statement that Sgt. Santos A. Cardona harassed prisoners for "nothing more than the entertainment of the accused and the enjoyment of the other corrupt cops serving on the night shift at Abu Ghraib."

But defense attorney Harvey Volver said Cardona, a 32-year-old military policeman from Fullerton, Calif., followed the law and obeyed orders at a time when the Pentagon was pressing for intelligence and the chain of command at the prison was broken.

"No one had any earthly idea who controlled whom," Volver said in his opening statement.

Cardona is accused of letting his tan Belgian shepherd, Duco, bite detainee Mohammed Bollendia on the leg badly enough to require stitches, according to charge sheets and investigators' reports.

Cardona also is accused of using his dog to harass and threaten another detainee, Kamel Miza'l Nayil, in violation of the Uniform Code of Military Justice.

Cardona is charged with assault, dereliction of duty, maltreatment of detainees, conspiracy to maltreat detainees and lying to investigators in late 2003 and early 2004. If convicted on all counts, he faces up to 16 1/2 years in prison.

As testimony began, former Staff Sgt. Ivan L. "Chip" Frederick II said he saw Cardona's dog bite Bollendia twice after the prisoner attacked a military police officer in a prison hallway.

Frederick, now a private serving an eight-year sentence for his role in the scandal, said the MPs probably could have subdued Bollendia without the dogs but that he believes the canines were used properly.

Frederick also testified Cardona told him that he and Sgt. Michael J. Smith were having a contest to see how many detainees they could make urinate on themselves by terrifying them with the dogs.

Cardona was assigned to the 42nd Military Police Detachment at Fort Bragg, N.C., and is the second Army dog-handler charged in the scandal.

Smith, of Fort Lauderdale, Fla., was convicted at a court-martial in March of maltreatment, conspiracy, dereliction and an indecent act. He was sentenced to six months in prison.