Actually, after reading JnCC's post, I take back what I said. Don't go to the hosts first. Get the doctor you saw to send the report to the police and let them handle it. JnCC's right: going to your hosts with the threat of going to the cops sort of constitutes tampering with evidence in a way.
I have a habit of believing the best of everyone, and always hoping that every person has some decency in them, but that's not always useful or realistic. This is just such an occasion. My suggestion to sort things out between yourselves is my knee-jerk reaction, because my motto seems to be "Can't we all just...get along?" JnCC's suggestion is far more practical and realistic. While I might not always agree with the way he calls a spade a spade
I can certainly appreciate it in this instance.