ustanoviti

1. to establish; to ascertain; to find out
   Lekar je ustanovio da nema ništa ozbiljno. — The doctor established that it was nothing serious.
   Policija još nije ustanovila uzrok požara. — The police haven't yet determined the cause of the fire.
2. to found; to establish; to institute
   Grad je ustanovio nagradu za mlade pisce. — The city established an award for young writers.

In the sense 'find out' it is often followed by a da-clause: ustanoviti da…