"If the cliche about secret serial killers is that they seemed so normal," said Ryan Tate in Gawker, Philip Markoff could be the stereotype's poster child. Boston police arrested Markoff in connection with the killing of a masseuse hired through Craigslist. To read Markoff's Facebook profile and the website for his wedding -- he was to wed college sweetheart Megan McAllister in August -- you'd think Markoff was just "a considerate if WASPy groom."

If Markoff really is the Craigslist killer, said the technology blog AppScout, he may have been "fingered by his own Crackberry addiction." The man shown in a string of surveillance photos at the hotel where Julissa Brisman, 26, was killed on April 14 is clutching a Blackberry. Police reportedly tracked their suspect by following his online trail.

"We're really horrified and saddened that our community services have been associated in any way with a crime of violence," said Craigslist founder Craig Newmark in The Huffington Post. We're committed to helping investigators catch criminals who use Craigslist. This kind of thing is rare -- "maybe most crooks realize how vulnerable they are using our site."