An HIV-positive Maryland man was intentionally transferring the virus to women he targeted on dating apps, police say.

Rudolph Jericho Smith, of Frederick, was arrested and charged on Monday after a 21-month long investigation.

The Frederick Police Department received a tip-off in July 2017 that 34-year-old Smith was seeking out women on various apps and websites and having sexual relations with them, fully aware of his diagnosis.

The complaint came from a woman who said she tested positive for HIV after having sex with Smith, Frederick News-Post reported.

Police have so far identified and contacted three more alleged victims, who met Smith on Backpage and Bumble, as well as offline.

Smith was indicted by a Frederick County grand jury this week on four counts each of assault in the first degree, reckless endangerment and knowingly transferring HIV to another person.

Although the charge has been filed there before, Frederick County State’s Attorney Charlie Smith said it is highly unusual.

'It only comes up every several years that we’ll see a case like this,' Charlie Smith told the News-Post.

The evidence to secure Rudolph Smith's arrest took a considerable effort to obtain, owing to the highly sensitive nature of the case and the difficulty of tracing victims through numerous dating sites.

Detectives also had to file requests for medical records in order to confirm their timeline and victims' statements, Lt Kirk Henneberry, who oversaw the investigation, told Frederick News-Post.

In order to secure a conviction, prosecutors must provide irrefutable and watertight evidence that the suspect knew they were HIV-positive.

Smith received his diagnosis in 2014 and he later confirmed his HIV status to detectives, Frederick News-Post reported citing a Frederick County State’s Attorney’s Office press release.

Knowingly transferring or attempting to transfer HIV to another person carries a $2,500 fine and up to three years in prison.

Police have asked anyone who may have had a sexual relationship with Smith around or after July 2017 other potential victims to come forward.