The MSHSL said he died in Hibbing Tuesday, and had tested positive for COVID-19.
The suspect lived near the victim and went to school with her children.
The suspect, now 52, is accused of killing a woman 34 years ago.
Police are still on the lookout for one of the suspects involved.
The 61-year-old has not been identified.
The 36-year-old is facing sentences of 30 and 25 years for two counts of sexual assault.