Italian police made the incredible discovery on Saturday afternoon when they found a 33-year-old Egyptian woman and her three children, aged three, seven and nine, living in a cluttered fifteen square metre garage beneath a block of council houses in Monza.
The discovery was made after his other wife - a 47-year-old Egyptian with whom he had another three children, aged between three and ten, called the police, but for an entirely different matter.
In fact, the 50-year-old's first wife had no idea his second family was living in the garage. She called the police because she spotted the man - who had a restraining order put against him last year for mistreating her and their children - hanging around outside the building and thought he was stalking her.
But it turned out he was just visiting his other family in the garage below.
When the police showed up, he told them he was not there to bother his first wife but to see other family, and led them to the garage, where the family had been sleeping on old blankets strewn across the floor.
But despite the squalid conditions, police told Il Fatto Quotidiano that they were not being held captive and that they were "free to come and go as they pleased".
They didn't know how long the man's second family had been in Italy, but they suspect the family had been living in the garage for at least "a few weeks".
The four were taken to hospital, but found to be in good health.
Meanwhile, the man is being questioned as police try to piece together the extraordinary set of circumstances that led to his second family being housed in the garage.
For now, magistrates have charged him with breaking the terms of his restraining order but they are still awaiting confirmation of his second marriage before they can charge him with bigamy.