Corrected entry: Catherine tells the snuff film producer that they know he was infected with HIV by accidental blood transfer from the actress he killed because they 'tested the DNA of the HIV'. No, they didn't. HIV is a retrovirus - it has no DNA. It has RNA, a far simpler nucleic acid which is completely distinct from DNA. Catherine is a scientist, trained and experienced in genetic 'fingerprinting' - she would never make a mistake like that.