
Prosecutors in Halle are looking for an anonymous character in the game who sold images of child pornography and paid for virtual sex with others players who had child-like avatars.
"We are trying to find out the identity of this person because what is being offered is nothing short of child pornography," chief prosecutor Peter Vogt said on German television.
Virtual child pornography is a crime in Germany carrying a prison sentence of up to five years.
Recent figures from market research firm comScore show that well over half of active Second Life users are from Europe, with the vast majority based in Germany.
Details of the offences came from an investigation by German television programme Report Mainz.
Reporter Nick Schader paid a small fee to attend a child pornography meeting in Second Life which led to contact with players trading real child pornography.
San Francisco firm Linden Lab, which runs Second Life, promised to find those responsible and turn them over to the police.