by Max Brantley
One of Henderson's daughters, Savannah Blankenship, told NBC News that her family was "very taken by surprise" to wake up to the news militants had claimed responsibility for killing her father.
"It's just a little overwhelming," she said, adding that her family had found it difficult to get information about how her father died. All her family was told in August was that Henderson had been murdered, she said.
When asked whether the family believed the group's claims, Blankenship responded: "I have not a clue."