Seattle police arrested a 24-year-old Kent, Wash., man they say placed a sex-and-murder ad on Craigslist.

Police say they were notified last Wednesday of an ad labeled "a strange desire" posted in the "casual encounters" section of the listing for the Seattle-Tacoma area.

The ad indicated a man wanted to have sex with a woman, then kill her.

Vice detectives exchanged e-mails with the man. They made arrangements for him to find the victim Monday at a motel and arrested him when he showed up with a heavy chain and a knife.

Shawn Tyler Skelton faces attempted murder charges. Bail was set Tuesday at $1 million.

The latest Craigslist scare comes days after Boston University medical student Philip Markoff was charged with using the classified ad site to lure women selling erotic services to hotel rooms, where police say he attempted to rob them at gunpoint to feed a gambling habit.

Markoff, 23, is accused of killing one of the women, New York City masseuse Julissa Brisman, when she tried to fight him off in a luxury hotel in Boston on April 14.

He has also been charged with the robbery four days earlier of another masseuse at a different Boston hotel.

Markoff, dubbed the accused "Craigslist Killer," will likely soon be charged in a third case of attempted robbery of a Las Vegas stripper in Rhode Island.

Click here for photos.

Click here for charges against Markoff. [FindLaw: Commonwealth v. Markoff]