Assuming of course, that they are confessing them in the first place, which is a dubious proposition.
Well, yes.
But some do.
Confession secrecy is actually huge in Catholic Church. There are saints, who prefered torture and death to revealing confessional secrets. So now, North Dakota is going to create many new saints?!
Believe or not, lot of criminals care about the eternal life and how not to get to hell. But, instead in North Dakota, they can just drove to South Dakota and confess there.
I remember a criminal case from Europe - in very Catholic country.
The prosecutors actually presented evidence that the murderers went on pilgrimage to some famous sanctuary where they could get absolution. Just going there (they could not interview the priests) was actually part of the prosecution packet. (There was more evidence of course.)