A friend of mine collects criminal memorabilia – Crippen’s watch and crucifix, that sort of thing. I’ve never been tempted to splash out. For one thing, I’m not sure you can guarantee the provenance.

Apparently, there is also a market for paintings by criminals: the more violent the man the higher the price. So anyone who bought a Kray painting 10 years ago would probably be doing very nicely.

There’s one bit of criminolania, however, I’ve always rather fancied. It’s a hat which has been on display in Detroit for almost 75 years. It belonged to Duncan Cameron McCrea who became an assistant prosecutor in Wayne County in 1924 at the time of prohibition, and the battles of Detroit’s Purple Gang with the Little Jewish Navy who fought over the distribution of booze coming in from Canada.

It took him 11 years and a good deal of self-publicity before McCrea, who had a reputation as Detroit’s wall against organised crime, managed to get elected as county prosecutor.

The next six years were just as high profile until in 1939 Janet McDonald, the girlfriend of a Detroit detective, committed suicide leaving a note that her boyfriend was a bagman for racketeers. McCrea pooh-poohed such a suggestion, but in 1940 a one man grand jury handed down an indictment charging him with accepting bribes in relation to gambling and prostitution in the county.

The story goes that when he was removed from his office on the fifth floor of the police headquarters he didn’t have time to take his straw snap-brimmed, light brown banded panama hat with him.

It remained in the office cupboard until 1967 when the office transferred to 1300 Beaubien St and the hat went with the staff. In its new home it was on view in a clear box as a reminder that when the incumbent prosecutor left his job it should be with dignity and with sufficient time to take his hat with him.

McCrea was sentenced to four-and-a-half to five years along with his co-conspirators, the mayor Richard Reading and the county sheriff Thomas C Wilcox, who once had the bright idea that to stop an epidemic of chicken thefts the birds should be tattooed with serial numbers.

McCrea served nearly four years and before his death in 1951 made several unsuccessful attempts to get back into politics.

James Morton is a writer and former criminal defence solicitor