Police lost track of Antonio Pelle, 48, when he was not found in his hospital bed in the city of Locri in the southern Calabria region where he was admitted because he was suffering from a form of anorexia which provoked weakness and caused difficulty for him to walk.
Anorexia, most prevalent among teenage girls, is characterized by an obsession with body weight and the resulting refusal to eat.
Pelle, also known by nickname "Mamma" was released from prison and given house arrest in April after a court in the city of Reggio Calabria said no prison was equipped to care for the inmate who weighed less than 50 kilograms.
Pelle was sentenced to 13 years for cultivating marijuana and 13 years for his involvement in a feud between crime clans that culminated in the August 2007 headline-grabbing 'Ndrangheta massacre at a pizzeria in the German city of Duisburg.
The 'Ndrangheta is Italy's wealthiest and most powerful crime syndicate with its roots in the Calabria region.
Pelle was arrested in October 2008 in a farmhouse surrounded by more than 100 marijuana plants.