Such an accusation was held by his Golden Dawn party, which was linked to the murder of left-wing rapper Pavlos Fyssas in 2013.
In a trial lasting just over five years, Lagos and another thirty or so leaders of the outlawed political force were convicted for their participation or links to the incidents.
Following his request, during Wednesday’s appearance to a judge in Brussels, the Brussels justice system took 15 days to decide on his extradition to Athens.
Lagos was arrested on Tuesday by an international mandate after the European Parliament lifted his immunity.
The Belgian Prosecutor’s Office clarified in a statement that there is still no date for the next hearing.
Golden Dawn’s leader Nikos Michaloliakos is in jail, but the organization’s number two head, Christos Pappas, is on the run.