Hakkarainen received a conditional sentence of one year and nine months for a similar crime in December 2005.
Prior to moving to Rovaniemi in 2002, Hakkarainen lived in Tikkakoski, Äänekoski, Mäntä, Joensuu and Keuruu.
Police are still searching for 12 women who they suspect may have had unprotected sex with Hakkarainen. So far 18 women have come forward. Three of them have contracted HIV. Four are still awaiting test results, and 11 have tested negative for the virus.
Officials say they hope the other women contact police and get tested. The Rovaniemi police number is 016 329 5111.