Prosecutors say 30 people may have contracted HIV from a 22-year-old student who knowingly had the disease and secretly filmed himself infecting others.
Michael Johnson, aka 'Tiger Mandingo', was charged in October with exposing partners to HIV in Missouri.
However, police allege they have only just worked out the former Lindenwood University student secretly set up a camera to film himself having sex with others.
"On that laptop were 32 videos (of partners) engaged in sexual acts with Mr Johnson," said St Charles County prosecutor Tim Lohmar.
“It’s safe to say that numerous of those videos were taken inside his dorm room; we know that because we recognise the furniture.”
Police say those partners were unaware Johnson was HIV positive and they were being filmed.
They also allege he met his sex partners on his Facebook, Instagram and Twitter accounts, where he goes by the name 'Tiger Mandingo'.
Prosecutors are trying to identify victims, urging them to come forward as a matter of public health and justice.
Students say they are shaken up by the news, especially because it allegedly occurred on university.
“I think it’s really scary, thinking someone like that is on campus, not thinking about others,” student Jenny Counts told KMOV.
If convicted of knowingly transmitting HIV, Johnson could face life in prison.