The F/O was the PF and under supervision, since new to the aircraft. I've known him for years as a good and professional colleague. The PIC, who survived (as did the CA and the sole PAX), is under shock and does not remember much apart from grabbing the checklist after liftoff and then seeing 90° bank to the right.
Very sad story. He was so happy for his new job...
Let's hope we find out what the cause was and that something can be done to avoid this from happening again.