In the US they have university police who investigate crimes. In the case of this gang rape in a fraternity house, very serious allegations were only investigated internally, and punishments handed down included "writing essays".
It seems that the actual police only became involved much later.
In the UK, universities are under pressure to deal with incidents of sexual assault "in-house", but arguably they should only be handled by experts within the criminal justice system.
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Details emerge in case of former Cornell student alleging gang rape by fraternity members - CBS News