A Marine who acknowledged being a willing participant in the kidnapping of an Iraqi man last April said he and his fellow servicemen were on a mission to "send a message to the insurgency."

Lance Cpl. Robert Pennington, 22, told a court-martial he knew at the time of the kidnapping that it was wrong, but he participated nonetheless because he and his fellow Marines were sick of suspected insurgents slipping through the justice system.

The squad was accused of dragging Hashim Ibrahim Awad from his home in the rural town of Hamdania, and shooting him. Investigators believe the servicemen tried to cover up the killing by planting an AK-47 and a shovel by Awad's body to make it look like he was an insurgent planting a bomb.

"We treated what was to be done as a mission, planned it, briefed it and executed it as a mission," Pennington testified Tuesday after pleading guilty to conspiracy and kidnapping.

He was to return to the military courtroom Wednesday to continue testimony.

Pennington, of Mukilteo, Wash., entered the two pleas under a pretrial agreement. He also pleaded not guilty to murder, larceny and housebreaking, charges that will be dismissed if he completes terms of a plea bargain requiring him to testify for the government and remain on good behavior.

Pennington, the squad's radio operator, said his squad agreed if it could not capture a suspected insurgent, it would seize and kill someone else.

"If we could not catch Saleh Gowad or his brothers, it was another step down to kill another military aged male in the town," Pennington said. "We felt that capturing them was an exercise in futility ... they would just be released a few days later."

The squad was unable to kidnap Gowad because an elderly woman confronted them by his house, Pennington said, so the troops moved down the road to Awad's house.

Pennington testified he and three other troops led Awad from his home. When Awad asked them what was happening, they told him he was being taken to Abu Ghraib prison for the night and would be returned the next day.

Pennington said he helped force Awad into a roadside hole and tried to silence the protesting victim by holding his hand over his mouth.

Pennington said he did not fire at Awad, and was radioing his patrol base when the shooting started. He said he remembered squad leader Sgt. Lawrence G. Hutchins III firing "about three" bullets into Awad's head.

Hutchins, of Plymouth, Mass., is awaiting trial on murder and other charges. His lawyer has said he does not think Hutchins did anything wrong.

Pennington is the sixth squad member to plead guilty in the case. Three of the Marines and a sailor have pleaded guilty to lesser charges as part of plea deals. They were sentenced to less than two years in prison, but were required to testify about the killing.

Another Marine, Cpl. Trent D. Thomas, pleaded guilty last month to murder, but withdrew the plea ahead of his sentencing last week. He said he believed he was following orders.

Pennington, who was on his third tour of duty in Iraq, faces a maximum life sentence, though this term is likely capped by the pretrial deal.