What hints are we given that this captain is Juan?

The Captain asks about her daughters,

What she never learned was that this captain was the same Juan Alejandrez who had carried off her daughter Gertrudis some months before. They were even on that score, for the captain remained ignorant of the large number of chickens that Mama Elena had hidden behind the house, buried in ashes. They had managed to kill twenty before the troops arrived. Ch 5