Vasil Mihaylov, known as the "prosecutor's son", is appealing against his arrest, and his case has now reached the Sofia Appeal Court, the court says.
At issue is the permanent "detention in custody" order Kyustendil District Court placed on him under a European arrest warrant from Greece.
Greece is investigating him over claims he took part in an organised crime group, armed robbery and causing grievous bodily harm. Under Greek law, these crimes carry a possible life sentence.