Niger ambush investigation expected to be complete in January, Pentagon says The U.S. soldiers were ambushed by an ISIS-affiliated group in Niger in October.

 -- The Pentagon has contacted the families of the four U.S. service members killed in Niger to update them on the timeline of the investigation into their family member's death.

Staff Sgt. Bryan C. Black, Staff Sgt. Jeremiah W. Johnson, Staff Sgt. Dustin M. Wright, and Sgt. La David T. Johnson were killed on Oct. 4 when their patrol of 12 U.S. and 30 Nigerien forces was ambushed by an ISIS-affiliated group outside the village of Tongo Tongo.

U.S. Army officials told the families that the investigation is expected to be completed in January, according to a statement released on Wednesday by the Department of Defense.

The investigation is being led by U.S. Army Maj. Gen. Roger Cloutier, U.S. Africa Command's chief of staff. Cloutier's staff will travel to locations in the U.S., Africa and Europe "to gather information related to the investigation," the statement said.

"Once the investigation is completed, briefing the families of the fallen will be the Department's first priority," the Pentagon said, adding it's "committed to a thorough and detailed investigation" into the service member's deaths.