establish
US /ɪˈstæb.lɪʃ/
UK /ɪˈstæb.lɪʃ/

1.
2.
show (something) to be true or certain by accumulating facts
:
•
The police were able to establish his guilt.
•
It's important to establish the facts before making a decision.
show (something) to be true or certain by accumulating facts