A day before Occupy Wall Street hopes to shut down New York and cities across the country in massive May Day protests, the NYPD visited at least three activist homes in New York and interrogated residents about plans for tomorrow's protest.

Today "there was definitely an upswing in law enforcement activity that seemed to fit the pattern of targeting what police might view as political residences," said Gideon Oliver, the president of the New York Chapter of the National Lawyers Guild, which offers legal to support to Occupy Wall Street. "They were asking what are your May Day plans, do you know who the leaders are—these are classic political surveillance questions."

Oliver said the National Lawyer's Guild is aware of at least five instances of NYPD paying activists visits, including one where the FBI was involved in questioning. (He wouldn't elaborate.) We spoke to three of these activists.

In the first case: activist Zachary Dempster said that six NYPD officers broke down the door of his Bushwick, Brooklyn apartment at around 6:15am this morning. Dempster said they were armed with a warrant for the arrest of his roommate, musician Joe Crow Ryan, for a six-year-old open container violation. But Dempster believes this was an excuse to check in on him, as he'd been arrested in February at an Occupy Wall Street Party that was broken up by cops, and charged with assaulting a police office and inciting a riot.

After running his ID, a detective questioned Dempster in his bedroom for about five minutes about tomorrow's May Day protest, he said.

"They asked what I was doing tomorrow, and if I knew of any activities, any events—that was how the conversation started," Dempster said. Dempster said he's not planning doing much, as his case from February is still open. Dempster's roommate was also asked about him and May Day.

About an hour later, an activist friend of Dempster's who runs in anarchist circles said his apartment in Bed-Stuy, Brooklyn, where he lives with a half-dozen other activists and Occupy Wall Street organizers was visited by six NYPD cops—possibly the same ones. The activist said police used arrest warrants for two men who no longer lived there as pretext for the raid. The officers ran the IDs of everyone who was in the apartment, then booked our source when they discovered he had an outstanding open container violation. Police never asked about Occupy Wall Street or May Day, but our source said the message was clear: We're watching you.

"We obviously don't think it's an accident that it happened the day before May Day, where people in the house are organizers," he said.

This afternoon, NYPD also visited the home of Greek anarchist artist Georgia Sagri, who has been part of Occupy Wall Street from the beginning and led the occupation of a SoHo art gallery last October. Turns out she was giving a press conference about May Day at Zuccotti Park at the time. Police waited for about an hour outside her home, then left.

"My roommate gave me a call and told me the NYPD was looking for me," Sagri said. "Since that time, I didn't go home. So I'm basically on the street. My May Day has already started which is fine, I don't mind." She said she has no idea why NYPD visited her.

This isn't the first time NYPD has been criticized for aggressive surveillance of protesters: The NYPD infiltrated activist groups around the country before 2004's New York Ciy Republican National Convention. And The New York Times has ably detailed the extent to which NYPD has harassed and spied on Occupy Wall Street protesters.

"The intention behind this I'm sure is to try to create fear and silence dissent," said Marina Sitrin, a lawyer and member of Occupy Wall Street's legal working group, "and to keep people from coming out into the streets."

[Image via Getty]