I would really love a link to that paper. A quick google search didn't turn up what I was looking for.
I did manage to dredge this link up, which says that in 1973, Minnesota had the lowest high school drop-out rate in the nation, and the third-lowest crime after Iowa and Maine.
http://news.minnesota.publicradio.org/features/2003/08/12_cu...
Which is no smoking gun, but is suggestive. I'm sure someone could do a deep dive on academic literature in criminology and turn it up, but it won't be me I'm afraid.