Dude admitted to raping his sister, unsure of what to do

My sister has a friend in Texas, and I'm not sure what to do because her brother(M17) admitted over text that he raped his sister(F16), and I have proof but we don't know his name, just the general location, something needs to be done but I don't know how to help, let alone if I should. We live nowhere near them as well

EDIT1- OH MY GOD HE SAID MORE?????? I AM NOT ALLOWED TO POST THIS SHIT

EDIT2- cops got him. Thanks guys