Trump was referring to the news stories being reported at that time. The democrats used his blunt truthful language to slander him for political gain. http://www.breitbart.com/big-journalism/2015/06/17/media-meltdown-commences-after-donald-trump-goes-full-honey-badger-on-immigration/

It is well documented that both illegal immigrant criminals are raping people, and that they illegaly return after being deported and commit more crimes. http://www.breitbart.com/texas/2016/05/26/previously-deported-illegal-alien-child-rapist-captured-new-mexico/

The human smugglers also rape the immigrants they bring across the border, so often that there are 'rape trees' they use to hang evidence to scare current victims. http://www.breitbart.com/texas/2016/04/25/rape-trees-dead-migrants-consequences-open-border/

These things are not brought up in 'polite' conversation, but it does not mean that they are not true and happening right now due to the insecure border.

Nobody ever called Trump a racist, until he ran for office against a Democrat.