Shortly after 9/11, the New York police department launched a massive surveillance program. Here's how it worked: the NYPD dispatched a vast network of plainclothes officers and informants – known as “rakers” and “mosque crawlers” – into Muslim neighborhoods, to eavesdrop on conversations in mosques, student associations and cafes.

In their new book Enemies Within, Pulitzer-winning journalists Matt Apuzzo and Adam Goldman detail the radical counterterrorism plan that transformed New York’s privacy and allowed the NYPD infiltrate and surveil Muslims around the city.

Their investigation, based on hundreds of previously unpublished internal memos, and exclusive interviews with intelligence sources, shows how many of the NYPD's strategies aren’t even close to being useful, functional, or successful.

Today between 2 and 3pm ET (7-8pm BST), Goldman and Apuzzo will take your questions about the strengths and weaknesses of America's counterterrorism efforts in the wake of 9/11, and reveal some of what they learned during their investigation.

We asked them a few questions to get started but post your questions in the comment thread below.

For our readers who haven’t yet read the book, describe the findings of your investigation in 6 words.

Domestic spying didn't save the day.

Did you discover any evidence that the surveillance plans actually worked?

The NYPD was uniquely prepared to unravel this plot. The Intelligence Division, with help from the CIA, built programs that used plain-clothes detectives to eavesdrop in Muslim neighborhoods, to map where Muslims work, shop, live and pray, and to document their views on subjects like the State of the Union address and the CIA's use of drones. Police informants recorded sermons inside mosques and collected license plates of everyone who prayed there. Police kept files on Muslims who changed their names to sound more American, as well as new converts to Islam who took on Arabic-sounding names.

Did anyone in the NYPD object to spying on Muslims?

Nobody could object because nobody knew about it.

Unlike other police departments, the NYPD does not tell the City Council about its operations. It does not reveal its organizational chart, its tactics or its files. The Intelligence Division has never been audited. Just as we're seeing with the NSA debate, the public was left in the dark about how extensively the government was keeping tabs on people.

What do you make of NYPD Commissioner Ray Kelly's full-throated attack on your work?

We've asked repeatedly to sit down and discuss these matters with Kelly. Even before the book came out, he dismissed it as fiction. We posted many of the NYPD's internal documents on our website http://www.enemieswithinbook.com so people can read them as they read the book and reach their own conclusions.

Are there reasons to think a new mayor will continue spying on New York-area Muslims?

It's hard to say. Domestic surveillance isn't a topic any politician wants to campaign on, not just in New York. Which is a shame because this is such an important discussion to have and people are much more ready to have it than the politicians.

Do you see any parallels in how the US government defends the NSA surveillance programs and how the NYPD defended its own?

For sure. The government response to both has been: It's all legal." And that's really beside the point. The bigger issue in all of these discussions is whether the public gives its consent, as a policy, to increasing levels of domestic surveillance. You can't give your consent to something that you don't know about. And since the City Council didn't know what was going on with NYPD Intelligence, Congress didn't know, voters didn't know, how can we be sure it's a good policy that works? Ironically the NSA has much more oversight than NYPD Intelligence, yet even some members of Congress say they were left in the dark about what NSA was doing.

Post your questions in the comment thread below. Matt and Adam will be back at 2pm to respond.

Highlights from the Q&A