The Mormons didn't kill the youngest children and babies, but brought them back with them and raised them as their own...

Some of those children still had memories years later...

And that is also covered in the book. As I said, I'm not quite finished with it, but they have several quotes from children survivors of the massacre.

What is fascinating about this particular investigation is that it looks closely at the motives of the attackers, and how what we know about the psychology of crowd control and the way people accede to authority explains a lot.

Now that I've finished the book, it turns out that they didn't exactly "raise them as their own." That was their intention, but when the massacre began being investigated, about two months after it happened, the children were all rounded up and sent to live with distant relatives.

The children did, indeed, have memories years later. Some were pretty grisly.

The book was really fascinating and I recommend it to anyone who is interested in the subject.