Question about Detective Joe Fontana

I have been a fan of every version of the franchise for over twenty years. I even watch the British version on occasion! But I always wondered if the writers ever explained HOW a cop from Chicago managed to get so much money that he could wear the clothes and drive the car that Fontana used. The FIRST thing you would think is that he was a crooked cop taking bribes, but that clearly wasn't the case. His voice wasn't that of an established family that would pass on a large inheritance (Fontana was clearly working class), but I never noticed any talk about where his money came from.

Maybe I missed some dialogue along the lines of, "My father wanted me to get an MBA to handle the family business, but I wanted to be a cop -- so I only got a quarter of the estate." Any ideas?

.
Mr Smith: "Like the rose trampled on the ground, you took the fall"