ARLINGTON (AP) - Friends and family are gathering to pay tribute to a North Texas Marine who died last week — apparently the first case of American troops killed by a missile fired from a U.S. drone.

The memorial service for 26-year-old Staff Sgt. Jeremy D. Smith was scheduled for Friday at Grace Community Church in Arlington.

Two senior U.S. defense officials have said the military is investigating how Smith and a Navy medic could have been mistaken for insurgents in southern Afghanistan last week. They were hit while moving toward other Marines under fire in Helmand province.

The drone in this case was armed and used to hunt and kill militants.

But Smith’s father, Jerry, has said he doesn’t want to place blame for what happened.

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