what does your heart/conscience say? it also depends on what kind of relationship you have with them. If you want to get this off your chest, you have to sit them down and tell them the truth. plain and simple. Once again, depending on your relationship with them, this may not be easy. On the other hand, this is the kind of news that could potentially ruin their trip. You also have the option of telling them on their way back from the trip. There is no easy answer. Its up to you to decide. I would be very concerned with the criminal record. depending on your age, it could affect your job prospects.