SAN DIEGO — The first combat tour of Private First Class John Jodka III ended four months after it began, when he and seven others were accused of kidnapping and murdering an Iraqi man.

Yesterday, the 20-year-old Marine infantryman was to appear at his court-martial, where he was expected to plead guilty to lesser charges and tell his account of what happened the night of April 26 in the Iraq town of Hamdania.

Jodka was charged with murder, kidnapping, conspiracy, assault, and housebreaking in the case, which involves six other Marines and a Navy corpsman. His attorney Joseph Casas said the San Diego area native would plead guilty to assault and obstruction of justice.

The Navy corpsman, Petty Officer 3rd Class Melson Bacos, pleaded guilty earlier this month to kidnapping and conspiracy.

At his court-martial, Bacos testified that he and the Marines were searching for a known insurgent who had been captured three times and released. The group approached a house where the insurgent was believed to be hiding, but when someone inside woke up, the Marines instead went to another home and grabbed 52-year-old Hashim Ibrahim Awad, Bacos said.

The squad took Awad to a roadside hole and shot him before planting a shovel and AK-47 to make it appear he was an insurgent planting a bomb, Bacos said. He was sentenced to a year’s confinement; murder and other charges were dropped.

According to government charge sheets, Jodka — the squad’s youngest and lowest-ranked member — was one of five Marines who shot at Awad, while others stood by and then helped cover up the killing.

“He was trained to follow his leaders and do as they commanded without questioning,” his grandfather Joe Snodgrass said Wednesday. “He was trying to be the best Marine possible.”

Mr. Snodgrass, 71, said Jodka has paid for any wrongdoing, noting his grandson has been locked in the brig since May.

“Whatever he may admit to, I think that the punishment he has already received is enough,” Mr. Snodgrass said, saying Jodka fought bravely in Iraq. Mr. Snodgrass noted his grandson’s flak jacket was peppered with bullet holes from when he’d been shot at on patrol.

Former Army prosecutor Tom Umberg said other Marines might follow Jodka’s lead and negotiate pleas.

“As the government’s evidence gets stronger, the defendants start to look around,” Mr. Umberg said. “They want to be sooner rather than later.”

However, Mr. Umberg said any decision to make a deal would be difficult.

“You are trained from day one to support your buddy, and also taught that there are certain values as a soldier or Marine you are fighting to uphold,” he said. “The resolution for a young man can be heart-wrenching.”

Five of the remaining six Marines face courts-martial. A decision on whether squad leader Sergeant Lawrence Hutchins will be referred to trial has yet to be announced.