Tony Earnshaw: The lucrative story of Al Capone and his family will run and run

In the case of the makers of Boardwalk Empire, a new TV mini-series about the early life and crimes of Al "Scarface" Capone, it was the notorious gangster's alleged grandson, Chris Knight Capone, who wrote to trade paper Variety with a most peculiar email.

Part of the missive said: "I have a problem with Film Companies using my grandfather's likeness and image for monetary purposes. Especially his name nonetheless. Please point this out in your article. I think the family would appreciate it."

In Boardwalk Empire Scarface is brought to vigorous life by the rising Liverpudlian actor Stephen Graham, who's just the latest in a long line of faces to portray the legendary Thirties bootlegger.

Over the years Capone has been played by everyone from Rod Steiger and Neville Brand to F Murray Abraham and Robert De Niro. Even his great-nephew Dominic Capone got in on the act.

There have been in excess of 40 films and TV shows. Possibly the first was an Indian production, in Hindi, featuring an actor named Samson as Capone. That was in 1942. Capone succumbed to syphilis in 1949. So it's a little late in the day for his family to be complaining.

But this is no ordinary declaration of familial connectivity.

For years Chris Knight has sought to prove his relationship to Capone. A property investor in New York, Knight (or Knight Capone as he is now calling himself) has demanded that Illinois authorities exhume the long-dead mob boss to allow DNA tests to prove his ancestry.

His primary purpose is to exploit the rights to Capone's likeness. And he should know about such things, given that he wears pinstripe suits and gold pinkie rings of the type favoured by the one-time Public Enemy Number One.

Knight's claim to a form of infamy came after his father died. He says it was later revealed that daddy was Capone's secret son.

For years the racketeer's family have believed that Capone had one child, Sonny, whose daughter Theresa Hall is still alive.

Theresa recently brushed off suggestions that she would be buying and reading a new biography of Capone written by his niece – and her cousin – Deidre Capone. And Al's great-granddaughter Katherine Seal commented: "He's been dead for 60 or 70 years. Why keep re-hashing it?"

Why? Because there's money in the dead.

Al Capone died leaving neither will nor inheritance. During his reign his empire raked in $100 million a year. Licensing his likeness and controlling TV shows, motion pictures and books could make a not inconsiderable amount for his descendants.

One thing's for sure: this one will run and run. And it will make a great movie...