Partners with Rhino, Mugsy was one of the Ventriloquist's henchmen. Being the more subtle of the duo, Mugsy and Rhino assisted their boss in two occasions. The first one was when Scarface committed several heists with clockwork precision, which attracted Batman's attention.
When the Ventriloquist was released from Arkham Asylum with a clean bill of health, Mugsy and Rhino awaited for Scarface to emerge. When it turned out that he wouldn't, however, they hired Hips McManus to impersonate Scarface and resurrect him. However, Scarface was upset with them and attempted to kill them, but Batman and Batgirl saved them and sent them to Stonegate Penitentiary.
A tall, thin, wide-eyed man, Mugsy was apparently the only member of Scarface's gang who fully understood that the Ventriloquist and Scarface existed as two separate personalities in Arnold Wesker's body, as evidenced by his refusal to execute the Ventriloquist on Scarface's orders after the puppet suspected him of betrayal.