Come on now….the Vatican City is a sovereign state (look it up)…
you just can't go and arrest someone in a sovereign state…wouldn't that be like someone from another Country arresting President Trump in the USA….i don't think so!!
So wouldn't that be under Geneva Laws, but who would make the arrests???
you can't arrest the Pope….kidnapping him possibly.
If you can't arrest the Pope….with enough evidence can you get him to surrender himself to a international court???