Newtown Connecticut AP

The family of Noah Pozner was mourning their 6-year-old, who was killed in the Connecticut school massacre, when their sorrow was compounded by outrage.

Someone they didn't know was soliciting donations in Noah's memory, claiming that they would send any cards, packages and money collected to his parents and siblings. An official-looking website had been set up, with Noah's name as the address, even including petitions on gun control.

Noah's uncle, Alexis Haller, called on law enforcement authorities to seek out "these despicable people."

"These scammers," he said, "are stealing from the families of victims of this horrible tragedy."

It is a problem as familiar as it is disturbing. Tragedy strikes and scam artists move in.

It happened after 9/11. After Columbine. After Hurricane Katrina. And after this summer's movie theater shooting in Aurora, Colorado.

Sometimes fraud takes the form of bogus charities asking for donations that never get sent to victims. Natural disasters bring another dimension: Scammers try to get government relief money they are not eligible for.

"It's abominable," said Ken Berger, president and CEO of Charity Navigator, which evaluates the performance of charities. "It's just the lowest kind of thievery."