My family is hiding something BIG from me?

Thumbing through an old family photo album, I came across a picture of an SS officer (Nazi). I asked my mom who he was and she screamed at me to throw it away. Subsequently I found a bunch of other pics in photo albums. I know I have family that left Germany for Paraguay and Switzerland. I probably should have put 2 and 2 together. My family won't talk about this and I have a feeling they are hiding something HUGE. What should I do?