Bizarre but apparently not completely rare...when I was staying in Barcelona a few years ago, there was a man who would come up on the stairs behind women who were exiting the metro stop and slash or stab their backsides. I believe he killed or nearly killed one woman because he impaled her with the long knife he used.
Believe it or not, this guy was caught, sentenced to jail - a really “severe” sentence of 10 years - and released in less than 5 because of the crazy European sentencing rules. Of course, he was caught doing it again. I don’t know the final dispostion of his case the second time around.
Hopefully, they threw him off a tall building.