The defense rested Friday in the court-martial of an Army dog handler who prosecutors said harassed prisoners at the Abu Ghraib prison in Iraq for his enjoyment and the entertainment of other military police officers.

Sgt. Santos A. Cardona, 32, of Fullerton, Calif., is charged with assault, dereliction of duty, maltreatment of detainees, conspiracy to maltreat detainees and lying to investigators. He faces up to 16 1/2 years in prison if convicted on all nine counts.

He is accused of letting his Belgian shepherd, Duco, bite detainee Mohammed Bollendia and of competing with another dog handler to frighten detainees in late 2003 and early 2004. He also is accused of using his dog to harass and threaten detainee Kamel Miza'l Nayil in violation of the Uniform Code of Military Justice.

A general visiting the prison urged guards and interrogators to use dogs "as much as possible" with detainees, a former supervisor testified Thursday.

The statement by Lt. Col. Jerry Phillabaum, a military police reservist who ran the Iraq prison in summer 2003, differed from Maj. Gen. Geoffrey D. Miller's testimony a day earlier that he encouraged the use of dogs only for custody and control of detainees.

Phillabaum, a defense witness, said under cross-examination that Geoffrey Miller "encouraged the use of dogs as much as possible in the normal operations of the confinement operations."

An expert witness for the defense also testified Thursday that Cardona was right to release his dog after Bollendia ran at and struck a military policeman.

Sgt. 1st Class Melvin J. Avis, a dog-handler certification trainer at Fort McPherson, Ga., said Cardona freed his dog to bite Bollendia because no one else moved to restrain the prisoner.

"The other MPs failed to do anything about the situation," Avis said. "They had the ability to control the situation; whether they hesitated or not, no one will ever know."

He said Cardona used the minimum amount of force necessary to gain control, the standard set forth in his training.

A prosecution witness, former Staff Sgt. Ivan L. "Chip" Frederick II, who is serving an eight-year prison sentence for abusing detainees, testified Tuesday that the MPs had taken Bollendia from his cell so the dogs could search it for weapons. The dog handlers had their animals bark at Bollendia when he refused to lie on the hallway floor, Frederick said.

The frightened prisoner jumped on former Cpl. Charles A. Graner Jr., striking him with his hands, Frederick said. He said Cardona told Graner to push Bollendia away and then released his dog, which bit the prisoner's right leg, grazing the skin. Bollendia again jumped on Graner and Cardona again released the dog, which bit the prisoner's left leg deep enough to draw blood, Frederick said.

Ten low-ranking soldiers have been convicted of abusing prisoners at Abu Ghraib, in many cases by forcing them to assume painful or sexually humiliating positions.