Unfortuntely it's not uncommon for abusers to capture their victims on camera. Some would conciously state its a trophy, others just want to savour the moment again for the future.
You will find that abusers tend to find eachother, either via an online chat, but mostly by chance. It also depends what position of social responsibility your teacher is in, as certain groups are likely to protect eachother (Judges, police, etc) as they have the power to do so, in such cases they often share their work.
Remember, it's not just about sexual gratification for these...people, it's about power, control and having absoloute authority over the moment aswell as the individual whose on camera. Holding a photo of someone in life changing situation is a huge statement in my opinion.
It's one thing to do this to a child, but taking a photo/video of that situation...it's just evil...pure evil.