All aspects of life are reflected in the collectibles markets, from the most beautiful artworks and best films to the greatest novels and most iconic people. And then there is the macabre...
Take a look at the memorabilia of noted collector David Gainsborough Roberts, for instance (you can read our exclusive interview with him here), and you'll find items linked to notorious mobster Sam Giancana alongside some of Marilyn Monroe's finest-ever dresses.
"Well, I've always been interested in crime and things along that line," David told us. "So I've got lots of things ... like [former US Public Enemy #1] John Dillinger's death mask. Crime seems to appeal to me - it just fascinates me. History is fascinating!"
And his collection isn't the only one which dabbles in the darker side of human nature...
'Follow the hat!'
Take a visit to Tammy Allen's classic car museum in Colorado, US, and you'll find a classic ambulance. Yet it's no ordinary ambulance, but the one believed to have carried President John F Kennedy's body after his assassination by gunman Lee Harvey Oswald.
Did this ambulance carry shot President John F Kennedy? Collectors think so
"I've always been interested in the Kennedys and everything that goes with them - it was like Camelot or the American Royalty," said Tammy in her interview with us.
"I just thought it was an interesting piece, that it would be so nice. It's interesting on its own, even if it wasn't [the ambulance that] supposedly carried JFK's body."
Elsewhere, both JFK's assassin Oswald and Jack Ruby, the man who later shot Oswald, have each made their mark on the collectors markets...
After JFK's murder in Texas caused shockwaves throughout the US, nightclub owner Jacky Ruby 'hastened the process of justice' by shooting Oswald at close range just two days later.
He was wearing a grey fedora hat with a black band. Bystanders' cries of "follow the hat!" became famous worldwide as he tried to make his escape.
The hat beat its $35,000 estimate in a Heritage auction in November 2009, achieving an impressive $53,800.
The assassin's assassin: killer Jack Ruby's fedora was sold for $53,800
Memorabilia from six feet under...
In easily one of the most bizarre sales the collectibles markets have ever seen, the simple wooden coffin understood to be Lee Harvey Oswald's final resting place sold to a mystery bidder for more than $87,000 in December 2010.
Oswald was buried in the box for 18 years following his death at the hands of Jack Ruby in 1963.
His body was later dug up in 1981 to disprove theories that Oswald's body wasn't in the coffin (dental records later showed that it was, in fact, his corpse).
'Hard men' from London to Paris
Which brings us to the criminal underworld... UK auctioneer Gary Don is preparing to sell letters written by London gangster Reggie Kray. The notes were written to a woman named Jane, with whom Kray had a 'relationship' from his prison cell in 1988.
Don may be onto something, considering that another collection of Kray photographs and letters last year sold for £20,780.
And this isn't the first time that a gangster's love letters have appeared at auction. While Reggie Kray remains one of the UK's most notorious criminals, Jacques Mesrine will forever be remembers as France's Public Enemy #1.
Yet the late bank robber's love letters to a former flame failed to find a buyer. Even though bidders pushed the letters' value to a significant €48,000, it was €2,000 shy of the lot's reserve.
Although Mesrine's letters underperformed, there is one criminal whose collectibles will always rule the roost - another Public Enemy #1, John Dillinger, whose life was once portrayed onscreen by Johnny Depp.
A rare letter written by Dillinger, while in an Indiana County Jail in 1932, realised over $60,000 - more than 10 times its opening bid of $4,000-6,000. The sale happened back in 2009.
Dillinger made his escape from the same County Jail on March 3, 1934, with a fake gun carved out of wood. A gun alleged to be the same wooden replica also sold for $19,120 that same year.
However, despite all this talk of criminal collectibles, never let it be said that justice is forgotten on the auction block...
The highest-selling piece of Dillinger memorabilia is a Colt Army Special revolver. The gun was used by an east Chicago Police Captain to fatally shoot the gangster in 1934. It sold in 2009 for an astonishing $95,600.