HIV positive student 'could have filmed himself having unprotected sex with more than 30 PEOPLE he met online'
Michael Johnson, 22, was charged with exposing gay lover to HIV
Police discover 32 sex tapes showing Johnson and a string of other people
Most films were made in room at Lindenwood University in St. Charles, Missouri, police said
31 unidentified men are captured in the explicit tapes
Investigation launched after a man claimed he caught HIV from Johnson