On Monday, Quick posted a photo of one of Nagtalon's paintings with a message, "Wanted by The Police!!" Then a version appeared with Nagtalon's driver's license photo on the "Wanted" sign.

"Now I am really freaking out," Nagtalon recalled. "Whoever this is knows where I live."

And, apparently, where his loved ones live. Quick's impatient e-mail from Wednesday referred to the street in New Jersey where Nagtalon's mother resides.

"Do we really need to do this the hard way?" Quick wrote.

Even now, Nagtalon still is not sure what's going on.

He has not been charged with a crime or formally warned. He has received no official notice that his paintings were seized or why.

Innovative policing?

I reached Quick at work, but he wasn't in the mood to chat.

Police Public Affairs Sgt. Ray Evers researched the case for me and read the anonymous apocalyptic AOL missives. I expected him to be horrified, but he praised Quick's "investigative talents" and was unconcerned by the tone of the e-mail.

"It is a threat. I see absolutely nothing wrong with this," Evers replied. "It's a new, innovative way to circumvent knocking your door down or leaving a message. I think it's fairly nice."

As for the warrantless raid?

"There was no search warrant," Evers confirmed, "because the items were in plain view."

Evers claimed Nagtalon had caused "tens of thousands of dollars, if not $100,000" worth, of graffiti damage but offered no specifics and didn't explain why, if Nagtalon was such a big fish, Quick offered to write him "a summary citation and call it a day."

The paintings were photographed for evidence and will be returned to Nagtalon "if he calls us and comes in," Evers said.

This, too, perplexed me, because Quick also asked me to tell Nagtalon to call, claiming, "We can't find him." The artist isn't hiding. He lives in Queen Village and blogs about his activities (http://eltoro215.blogspot.com). The police know his address; it's on the driver's license Quick used as part of his online harassment.

I relayed the saga to David Rudovsky, who declared: "Bizarre."

On the warrantless raid, the esteemed civil-rights lawyer said, "I strongly suspect that the police did not seek a warrant because they did not have sufficient cause for the seizure of the artwork. Instead, they did what the Fourth Amendment prohibits: a seizure of personal property without cause or judicial approval."

As for Quick's modus operandi?

"If the police had probable cause that Nagtalon was involved in graffiti, they could have simply obtained a warrant to secure his arrest," Rudovsky said. "It appears that they had no grounds for an arrest, and the methods used here are very troublesome."