Hi French here ! DO IT , kill it ! this is a thing. As a french I can only apologize in the name of all the sane people in france.
However know that there wasn't a single mention yet in the french controlled media.
I think one it's a grave crime from where there is no comeback possible, secondly the jail upkeep is useless (unless you need an organ bank, but it seems old) and 3 by killing them in provide a strong incentive to the deviants to behave and finally it's the only way to be sure (100%) that the thing will not do it again (who knows, jail break type of events).
so safe and secure : firing squad. and please don't forget to send the bill of this execution to his parents if alive.