Johnson Aziga was born in 1956 in Uganda and immigrated to Canada in 1984, settling in Hamilton, Ontario. He worked as a research analyst with the Ontario Ministry of the Attorney General. In 1996, Aziga was diagnosed with HIV. Despite his diagnosis, he engaged in unprotected sexual relations with multiple women without disclosing his HIV-positive status. Aziga's actions were in direct violation of public health orders issued to him in 2002 and 2003, which mandated that he inform sexual partners of his HIV status and practice safe sex. He met many of his partners in bars and clubs in the Hamilton area, and by his own admission, he had between 50 to 100 sexual partners during this period. Seven of these women later tested positive for HIV, and two died from AIDS-related complications. ​

In August 2003, Aziga was arrested after a woman he was involved with tested positive for HIV and identified him as a recent sexual partner. Following his arrest, a police investigation revealed that Aziga had unprotected sex with multiple women without disclosing his HIV status, despite being under public health orders to do so. In 2005, he was charged with two counts of first-degree murder, ten counts of aggravated sexual assault, and one count of attempted aggravated sexual assault. His trial began in October 2008 and lasted six months. On April 4, 2009, a jury found him guilty on all counts. The first-degree murder convictions were based on the deaths of two women who had contracted HIV from Aziga and later died from AIDS-related illnesses.

In 2011, Aziga was declared a dangerous offender, resulting in an indeterminate prison sentence. In 2023, the Ontario Court of Appeal overturned his first-degree murder convictions, substituting them with manslaughter convictions due to improper jury instructions regarding intent. Two aggravated sexual assault convictions were also set aside, with new trials ordered for those counts. Despite these changes, the court upheld his dangerous offender designation, citing his repetitive behavior, disregard for court orders, and lack of remorse.

Aziga has been denied parole multiple times, most recently in December 2024. The Parole Board of Canada cited concerns about his lack of remorse and empathy towards his victims, as well as ongoing issues related to his behavior in prison. He remains incarcerated at the Bath Institution in Kingston, Ontario. ​