adj : complete and without restriction or qualification; sometimes
used informally as intensifiers; "absolute freedom";
"an absolute dimwit"; "a downright lie"; [...]
adv : positively; "a regular right-down bad 'un"--Charles Dickens
I think you need to post this in the French/English forum, as this is English Only.
I think you are looking for the meaning of "right down to". If this is so, it is usually used to summarise a long list of possibilities…
The reasons people don't report crime range from "not believing that anything will be done" and "not wanting to get involved in court cases" right down to "being terrified of the police".
In this sort of structure the first two items mentioned would be the most common, and the last one would be the very least common. It is then understood by the reader that there is a long list of other reasons which have not been mentioned.
"right down to" = all the way down to.
Some francophone guesses (close to Kelly B's):
... jusqu'à être terrifié par la police
... à tel point qu'il était terrifié par la police
... au point d'être terrifié par la police
But is the original sentence complete, or is there something before?