WASHINGTON -- The Pentagon says it has recovered additional remains of Army Sgt. La David Johnson, who was among four U.S. soldiers killed in the African nation of Niger in October.

Bodies of three of the soldiers were found the same day they were ambushed; Johnson's body was found two days later. The Pentagon said Tuesday that a military investigation team found additional remains of Johnson on Nov. 12 at the site where his body had been recovered a month earlier.

The Armed Forces Medical Examiner positively identified the additional remains as those of Johnson, and family members were notified.

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The Pentagon did not provide details about the additional remains or indicate how the discovery might advance the overall investigation, which is expected to be finished in January.

Earlier this month, nervous villagers described the attack to CBS News foreign correspondent Debora Patta in the village of Tongo Tongo, where the ambush took place.

A village elder, who was so nervous he asked to speak at another location, told Patta that a few men suddenly appeared on motorbikes -- the preferred mode of transport for Islamic State of Iraq and Syria (ISIS) fighters in the region.

"It was just a few terrorists. We think, 'if it's just a few terrorists the soldiers can kill them easily,' but we didn't know there were so many more of them waiting nearby," the man said. He said there were about 20 motorbikes with two men on each, armed with either AK-47s or RPGs, and at least 10 vehicles that descended on the troops.