A Villanova University (Pennsylvania) history professor has been suspended and arrested on now up to 415 federal counts of possession of child pornography. The federal investigation was triggered when university police noticed visits to child porn sites from a public computer on campus. It is likely that the sites were overseas, and somehow got past the university anti-virus and site filters. Once in a cache, the legal offence of possession has occurred. A subsequent warrant and investigation showed images at home.
The CNN story is here. But the included video says he had been investigated for possession at home in 2012. It was not clear what had triggered the investigation (maybe the NCMEC database). He may have thought it “safer” to use a public computer.