If you believe John King, there’s surveillance video from Lord & Taylor department store of someone carrying and “perhaps” dropping a black bag near the site of the second bombing. What that means, I take it, is that they don’t have video of the drop itself but still frames of someone with, and then without, a backpack within a few seconds.

Investigators believe they have identified a suspect in the Boston Marathon bombings, a source who has been briefed on the investigation told CNN’s John King exclusively.

The breakthrough came from analysis of video from a department store near the site of the second explosion. Video from a Boston television station also contributed to the progress, said the source, who declined to be more specific but called it a significant development.

No images yet, but apparently CNN reported on air that the suspect has a dark complexion. This is … interesting too:

Suspect described as "dark-skinned male" says @JohnKingCNN, adding was given further description but won't inflame intentions by repeating

— Toby Harnden (@tobyharnden) April 17, 2013

There’s a briefing today at 5 p.m. ET. I don’t know if “identified” means they already have a name or if they’re going purely by description, in which case they’ll have to release the surveillance videos and risk “inflammation.” Sources tell the Boston Globe that they’re “very close” in the investigation, which I guess means that if they don’t have the name yet, they think they will soon.

Like Ace, I’m curious to see if the surveillance images match with any of the people identified in the 4Chan crowdsourcing of marathon Flickr photos. I skimmed through them this morning and nothing looked odd to me except the two guys with black backpacks and beige pants and boots standing next to each other. But that makes no sense: If you’re operating in concert, why make it easier for the feds to spot you by wearing similar clothes? Anyway, stand by for updates.

Update: I guess they have a name.

BREAKING: Law enforcement official: Arrest imminent in Boston Marathon bombing, suspect to be brought to court.

— The Associated Press (@AP) April 17, 2013

CNN’s now reporting that the arrest’s been made. Stay tuned.

Update: I find it morbidly strange that the bomber(s) didn’t have plans for a second attack immediately, i.e. within hours, after the marathon bombing. They know they’re probably going to get caught, and given all the cameras at the finish line, it’s probably going to be soon. If they’re willing to kill on Monday, why not yesterday or today before they’re pinched?

Update Hmmmmm.

Authorities investigating the Boston Marathon bombing said Wednesday they have developed “solid leads” and identified “a number of people” they want to talk to after viewing hundreds of hours of video, with one or two standing out.

Senior officials told NBC News that they were not prepared to characterize those individuals as suspects.

“We are zeroing in on some people,” an official said.

Investigators analyzing photos and video have found people carrying black backpacks and duffel bags and setting them down in the area where the bombs went off, officials said.

Sounds like maybe they’ve got one suspect on the L&T video but think he may have had a partner.

Update: NBC says there’s no arrest yet but the AP says the suspect’s already on his way to the courthouse.

Update: The plot thickens:

https://twitter.com/caseystegall/status/324587110831104002

Update: Total chaos:

CNN, citing THREE SOURCES: THERE HAS BEEN NO ARREST; NO ONE IN CUSTODY

— Dylan Byers (@DylanByers) April 17, 2013

Update: CBS has the first details of the surveillance vid, or so says their source:

At the site of what became the second explosion on Monday, surveillance video captured a man wearing a black jacket and gray hooded sweatshirt placing a backpack on the ground while talking on a cell phone, sources told Orr.

While the man was on the phone, the first explosion went off.

CBS News senior correspondent John Miller reports that authorities settled on one individual late Tuesday and are having discussions over whether to go public with identifying the person.

Update: Two tweets from the Boston Globe, posted within 11 minutes of each other, presented without further comment:

Boston Globe source reports suspect being taken to US District Court in South Boston.

— The Boston Globe (@BostonGlobe) April 17, 2013

US Attorney's office: There is no marathon bombing suspect in custody and no arrest

— The Boston Globe (@BostonGlobe) April 17, 2013

Update: A little more detail from a CBS affiliate:

Orr said authorities have video of a man in a black jacket on a cell phone, wearing a gray hoodie and a white baseball cap backwards placing a black bag at the second bomb site outside of the Forum restaurant on Boylston Street and then leaving the area before that explosion.

Orr said the man was on the phone at the second bomb site when the first bomb exploded.

Orr said the FBI looked at time man was on his cell phone and then went back and scanned all the calls made in the area to track who they wanted to talk to.

Are they suggesting that he detonated the bomb remotely by phone or that he placed a call to someone, or somewhere, that threw up a red flag?

Update: An FBI spokesman says nope, no arrests have been made. Who told CNN and the AP and the Boston Globe otherwise?

Update: Another strike against CNN: According to CBS, the suspect doesn’t have a “dark complexion.”

JUST IN: Man sought as possible suspect is WHITE MALE, wearing white baseball cap on backwards, gray hoodie and black jacket.

— CBS News (@CBSNews) April 17, 2013

Update: I skimmed the 4Chan gallery again but didn’t see anyone matching the CBS description. (There’s a guy in a white hat and black coat/pullover, but no hoodie.) The only one that looks close-ish is about two-thirds of the way down the page, with a bunch of flags in the foreground, of a man crouched against a wall with a black backpack. But the cap looks gray, not white, and I don’t see a hood, just a jacket with a big collar. I don’t think the suspect’s in any of those images.

Update: Indeed.

This … is CNN. http://t.co/n0SMTwZ03K

— Ed Morrissey (@EdMorrissey) April 17, 2013

Update: The “official” who told the AP earlier that a suspect is in custody is standing by that despite the FBI’s denial. Hmmm.