Even though I really don't think this is what happened here, just out of curiosity I did a search. I'm not going to quote any of the articles -except for the last one- because they are all are a bit graphic, but apparently -though rarely- they do eat humans. It appears that in most fatal alligator attacks, the cause of death is drowning from being dragged underwater:
By THE ASSOCIATED PRESS; LAKELAND, Fla. Jun 10, 2016, 7:37 PM ET:
http://web.archive.org/web/20160612...identify-body-found-alligators-mouth-39771017
Tyler Vazquez, Florida Today; Published 6:06 p.m. ET Dec. 7, 2015:
http://www.floridatoday.com/story/n...kills-barefoot-bay-burglary-suspect/76950238/
BY DARYL GAY ON OCTOBER 24, 2007:
http://www.gon.com/news/woman-killed-by-alligator-in-georgias-first-recorded-fatal-attack
By Michael D. Lemonick; Sunday, May 21, 2006:
http://content.time.com/time/magazine/article/0,9171,1196427-2,00.html
By Lindsey Bever; June 16, 2016: "What you need to know about alligator attacks, according to Jack Hanna"
"'The person is the last thing a gator wants to go for theyre afraid of human beings,' Hanna told Fox News. 'However, if it was hungry when this thing was happening, and there were ankles splashing around there, that to the gator is something the gator may want.'"
https://www.washingtonpost.com/news...cording-to-jack-hanna/?utm_term=.74865f7f60be
ETA: "List of fatal alligator attacks in the United States"
https://en.wikipedia.org/wiki/List_of_fatal_alligator_attacks_in_the_United_States