He saw Mr. Maitland turn around at the shouts and groans coming from his sons, who were glued to the play-off game, then back again. He said, “Ben Raven has been handling that. Most of the photos that have been uploaded aren’t relevant, they’re from around Magdalene College, yearbook photos, or photos with friends horsing around. We’ve found several photos of the crime scene, though, most showing no real detail because of the snow or because the cops had already established a solid perimeter around the Lincoln Memorial by the time they were taken. There was one, though, that was very close and very clear.”

“This is the photo,” Savich said, and brought it up onto the screen. “It’s the one Mrs. Cronin saw on the Internet that led Mr. Cronin to call us. It’s a close-up, straight-on view of Tommy’s face. Was it taken by Tommy’s killer or an accomplice, as a way of assuming credit and publicizing his killing? Or by someone who happened by at the right time and thought it would be cool to post it? There were no comments posted with it.”

Ollie said, “Or maybe even a cop.”

Savich said, “No one wants a cop to be the source. Believe me, Ben Raven is all over it. We’re dealing with all the photos by tracking down the IP addresses they were posted from. We have all of them already, except for this one.”

“What’s the holdup?” Coop asked.

Savich said, “Our techs have run into a roadblock, because whoever posted this photo used a bogus YouTube account and a proxy server to hide his tracks. We’re up against a computer nerd who knew we’d be trying to track his posting and knew how to protect himself. It’s the strongest reason we have to believe the killer or killers posted this picture, and not someone who happened by.”

Mr. Maitland said, “So why not get Spooner in on this? You’ve said yourself, Savich, it takes one to catch one.”

“You’re right,” Savich said.

Ollie said, “We’ve all heard about surfing the Web anonymously, using what they call anonymizers. What do they do exactly, Savich?”

“They’re a sort of privacy shield between a client computer and the rest of the Web, so you can protect your personal information by hiding your computer’s identity.”

Lucy said, “I read that a lot of the child pornography on the Internet is accessed through anonymizers.”

Savich said, “Like a lot of tools, anonymizers can be used for good or bad. If you lived in Iran or China, for example, where the Internet is severely restricted, using an anonymizer could save your life unless you make a mistake, and believe me, you’ve got to know what you’re doing. It gets even more complicated when you’re posting something—like a photograph. Then you need your own software to create a Web proxy and establish connections between chains of servers to hide your tracks. We’ve got a shot, though. I’ll get Spooner on it right away.”

Mr. Maitland said, “Spooner has liaised with the NSA for us in the past. If there’s a way to find this guy, Spooner will do it. Of course, there are new articles and postings about the Cronins all over the Web now—photos of the family, comments by Tommy’s friends at Magdalene College, as well as blogs and forums with theories about why he was murdered in such a public way. It’s a hodgepodge, though some of them are cruel. There’s even talk of a family curse, what with the death of both Tommy Cronin’s parents in the last two years, and now their only son.”

Ollie said, “All the Internet hype—I’m thinking it’s what the killer wanted. Savich, do we have anything else going besides Spooner tracing that upload to YouTube?”

“Not much. Ben has already spoken by telephone to two men and one woman he tracked down who’d uploaded what they could see of the crime scene on social networks. They told him they didn’t see anyone get close to the body because the police were keeping everyone at a distance by the time they arrived.

“Needless to say, we’d know a lot more about Tommy’s whereabouts last night by now if the weather hadn’t shut down the power and the roads, making it a no-go today.

“Sherlock and I will drive to Chevy Chase to visit Tommy Cronin’s grandparents tomorrow morning. Then we’ll go on to see Marian Lodge, Tommy’s aunt, who lives in Potomac Village in Montgomery County, Maryland. I’ve already spoken to them, and they’ll be expecting us.”

Maitland said, “The snow’s supposed to stop during the night, and then it’ll warm up again. Director Mueller called Palmer Cronin and has assured him and his wife that we will find whoever murdered his grandson. Guys, I don’t want to make a liar out of the director.”