John Baker, prosecutor, said Jodka had played a part in the killing of "a crippled man, a forgiving, simple man" leaving 11 children without a father.

He said Jodka had an opportunity to "stop the madness" but failed to do so.

Story fabricated

Joseph Casas, defence attorney, said the case "was not that simple," saying the soldier had been misled by older marines "he looked up to as heroes".

"I offer a sincere apology to the Awad family"

John Jodka, convicted US marine

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Prosecutors say the marines targeted Awad after an attempt to track down a suspected insurgent who lived nearby proved unsuccessful.

They said Awad was shot dead before the squad fabricated a cover story to  make it look as if he was an insurgent planting roadside bombs.

Jodka said he had decided to admit his guilt because it was "the right thing to do."

He said: "First and foremost, I offer a sincere apology to the Awad family. I'm [also] sorry for the trouble I've caused my family."

Murder charges

David Jones, a military judge, said Jodka would face an additional three-and-a-half years in custody if he failed to keep to a pre-trial agreement to give evidence against other soldiers on trial in the case.

Jodka became the second US serviceman to be jailed for involvement in the killing.

Navy corpsman Melson Bacos was given a one-year sentence last month after agreeing a plea deal that will see him testify against fellow soldiers.

So far three servicemen, including Bacos and Jodka, have pleaded guilty to charges related to the case.

A fourth member of the group is expected to enter a guilty plea next week.

The remaining four soldiers face murder and kidnap charges.