The ad, placed by aQuantive's DrivePM, promoted True.com--and in an especially bizarre coincidence, the creative, which carried the tagline "Get Soaked By Love," featured a young dark-haired woman who physically resembled St. Guillen, staring suggestively at the camera.

True.com, which bills itself as an especially safe dating service because it screens all members for a criminal history, said it would not have approved of having an ad accompany this particular story.

"If you're going to talk about online dating, you just wouldn't want to associate with someone being raped and murdered," said Cornell McGee, senior vice president, acquisition marketing at True.com. "You'd think that would be common sense."

True.com had only been using aQuantive's DrivePM to place ads for about three weeks, McGee said. He added that True.com would develop a policy to prevent ads from being displayed in stories it considers inappropriate.

But an aQuantive spokesman said that there was little that DrivePM could have done in advance to prevent ads from appearing alongside specific types of stories. "You can't predict the news," spokesman Steve Stratz said, adding: "news sites are a significant category online."

He also said that marketers who buy inventory on a news site do so for the audience, not the content--comparable to TV advertisers purchasing the first block of ads on the evening news.

Finding ad sponsors for hard news stories can be difficult precisely because marketers don't want to be associated with potentially disturbing articles. In fact, the True.com ad was included in the New York Post's run-of-site inventory--usually sold to networks at far less than the cost of more desirable inventory.

Not all visitors to the site Tuesday were shown the ad. DrivePM used its cookie-based behavioral targeting technology to display the ads to users who met certain criteria. The ad also appeared to be frequency capped, so that the same visitor didn't receive that ad every time the page loaded. By Tuesday evening, DrivePM had made arrangements to remove the ad from its rotation on the Post's site.

Other advertisers had display ads run in connection with the story--including JCPenney, Victoria's Secret, Verizon, and Weight Watchers, among others--but none of those marketers carry the baggage of potential danger the way online dating does. A study released Sunday by the Pew Internet & American Life Project found that 66 percent of Web users believe online dating is dangerous.

The New York Post did not return telephone calls for this article by presstime.

This news story is important. I recommend that everyone read it.