Police say a Maryland man knowingly spread HIV to four women after meeting them on dating sites and apps.

The Frederick News-Post reported Tuesday that 34-year-old Rudolph Jericho Smith has been charged with first-degree assault and reckless endangerment.

He also faces counts of knowingly transferring or attempting to transfer HIV to another person. The charge is a misdemeanor under Maryland's general health law.

Frederick police Lt. Kirk Henneberry said Smith was charged following a 21-month investigation. The time was needed to build the case.

He said detectives found alleged victims and scoured dating sites. They also filed requests for medical records.

Frederick County State's Attorney Charlie Smith said police and prosecutors must prove beyond a reasonable doubt that a person was aware they were HIV-positive before they can be charged.