SOME PEOPLE collect stamps, dolls or autographs. Others collect cars, coins or tea cups. And there's a guy in Australia who holds the world record for the biggest and longest-held collection of belly-button lint.

Paul Duffy collects mementos of murder.

And then he sells them, to whoever pays.

In a macabre industry whose merchants can be counted on two hands, Duffy put the Philly area on the "murderabilia" map last month when he began selling killers' artwork, letters and even hair, blood and fingernail clippings from his Coatesville, Chester County, home. (Other dealers hail from Georgia, Indiana and beyond.)

Duffy's Facebook page, called "Wholesale Murder," offers everything from pornographic pencil drawings by Philly's sex-strangler Harrison Graham to cult killer Charles Manson's prison-ID card to a baggie of blood belonging to Japanese cannibal killer Issei Sagawa.

Is it OK to profit from tragedy? Victim-rights activists familiar with such wares say, emphatically, "No."

"Collect all you want, but where I draw the line is when you're selling items that were obtained from serial killers and high-profile killers for profit," said Andy Kahan, a victim advocate in Houston who has crusaded against murderabilia sales since he learned of them in 1999. "People who sell these items profit from the pain, misery and grief that [murder] victims suffered and give the killers an infamy and immortality they do not deserve."

Kahan now is trying to get Facebook to shut down Duffy's page, as well as others who market murder on the free social-media site. Besides Wholesale Murder, at least five other such businesses have Facebook pages, including Supernaught, Murder Auction, Dark Vomit, Redrum's Autographs and Serial Killers Ink.

Kahan especially objects to the crime-scene photos that some sellers post. Serial Killers Ink, for example, earlier this month posted gruesome images of serial-killer John Robinson's decaying victims. "Enjoy!" the captions read.

"Can you imagine how that [victim's] family would feel knowing that their loved ones' horrific, graphic, degrading crimes are posted for all the world to see?" Kahan asked. "And there is no such thing as 'delete' here [on the Internet]."

Kahan has been successful in his previous murderabilia-busting battles, persuading eBay to ban such sales in 2001.

"Facebook is going to have to make a decision: Do they want to be associated with a business that profits off killers?" Kahan said.

But a Facebook spokeswoman said the content on the murderabilia pages doesn't violate Facebook's terms of use. For example, Facebook prohibits nudity in photos but not in artwork, and drawings - like Graham's sketch of a couple engaged in mutual oral sex - would be considered artwork, she said. And although Facebook forbids hate speech or anything inciting violence, content celebrating violence is allowed, she said.

"While some content may be vulgar and distasteful, distasteful content on its own does not violate our policy, as long as the pages are clearly marked so people know what they're seeing," she said.

Duffy sees little wrong with his entrepreneurial efforts.

"Maybe it's a little bit messed up to profit off crime, but it is a free society," said Duffy, 23.

The business grew out of Duffy's lifelong fascination with true crime, his own experience behind bars, personal tragedy and his addictive personality, he said.

As a teenager, he was a homeless drug addict who spent time in jail for assault, he said. He also lost a cousin and a high-school buddy to murder.

After writing to Manson a year ago, Duffy was undaunted when he got no response. Instead, he began writing to notorious criminals everywhere, collecting mementos for his own enjoyment. Once he'd amassed "well over 1,000" items, he said, he decided to start selling them.

Duffy regards his unusual enterprise as an investigation into criminal psychology.

"I talk to a lot of inmates. I consider some my friends," Duffy said. "I see how normal they are, how much I have in common with them, even though they killed nine people, maybe 10 people. I believe that me, you, everybody has a killer instinct in them, and if you get pushed around or wronged, you hit a snapping point. My interest is: What makes someone snap and commit murder?"

He's not worried about Facebook shutting him down. He has a website in the works -

"Everybody's interested in it because it's taboo and morbid," said Duffy, who also collects antique medical equipment and presidential seals.

"I have a Donald 'Pee Wee' Gaskins letter. He was a sick man; he raped and killed a 2-year-old girl," Duffy said of South Carolina's most prolific serial killer. "This letter is worth a lot."