New York City’s police department has emerged as one of the biggest opponents of Ted Cruz’s call to patrol specifically Muslim neighborhoods following the Brussels attacks. However, that same police department was a pioneer in monitoring American Muslims for over a decade following the September 11 attacks.

Following the Brussels attacks, Republican presidential candidate Ted Cruz, riding high off his appointment of a man who thinks President Barack Obama is secretly a Muslim, said counterterrorism strategy must be approached in the same way police deal with gangs, by having increased levels of patrolling and policemen in the area. “I’m talking about any area where there is a higher incidence of radical Islamic terrorism,” he said on CNN, shortly after the attacks.

The NYPD criticized the Texas senator almost immediately. The police department’s spokesman, J. Peter Donald, tweeted at Ted Cruz:

That message was reiterated by Police Commissioner Bill Bratton, who also lambasted Cruz for his comments. “The statements he made today is why he’s not going to become president of this country. We don’t need a president that doesn’t respect the values that form the foundation of this country,” he said. “As the mayor mentioned, I have over 900 very dedicated officers in this department, many of whom do double duty, and they serve as active duty members of the U.S. Military in combat, something the senator has never seen.”

While American Muslims were undoubtedly relieved that the country’s largest police force was standing up for them, the NYPD has not always seen Muslims under its jurisdiction as a trustworthy population. Less than six months after the September 11, 2001 attacks, now-former police commissioner Raymond Kelly created the Demographics Unit out of the skeleton of the police department’s Intelligence Unit, a specialized unit that once focused on breaking into drug and criminal networks.

The two men leading the unit’s transformation into an ethno-religious program were former CIA agent David Cohen and then-current CIA agent Larry Sanchez, despite a federal ban on the CIA engaging in domestic spying. The two were inspired by the Israeli military’s method of monitoring and controlling the Palestinian population in the occupied West Bank, according to an in-depth report by New York magazine. The system relied on thousands of “rakers” — informants who patrolled neighborhoods — collecting information as inconsequential as what TV channels were on at a local restaurant, what people wore, how often they went to pray, and a whole variety of other markers that mapped out the intimate details of thousands of Muslims in the city.

When the program was made public in a 2011 Associated Press report, American Muslims finally had confirmation of what they suspected for years since the 9/11 attacks: They were being monitored on the basis of their religion. Commissioner Kelly denied that religious identity played a role in what neighborhoods were monitored, saying only that the police force went where their investigations took them. Mayor Michael Bloomberg made a similar statement, saying that the NYPD did not consider religion in its policing, due to a ban on singling out communities due to their religion.

By that point, the Demographics Unit was expanding beyond its already broad mandate to monitor the entire Muslim population of the country’s largest city. They were monitoring anti-police brutality groups and antiwar protesters, cataloguing contact information and keeping tabs on their activities. Sanchez once even tried to share the information collected by the unit with the FBI, but his offer was refused after the agency discovered how information was obtained, which would have violated federal law.

Leonard Levitt, a columnist for Newsday known for his insider reporting on the NYPD, alleged that the NYPD hired another CIA official, Marc Sageman, as the department’s scholar-in-residence. That was not the only controversy surrounding the hiring. Even more troubling was the way in which Sageman was paid — through secret donations made to a secret non-profit whose directors included Stephen Hammerman, the NYPD’s former Deputy Commissioner of Legal Matters, and Joe Wuensch, Kelly’s chief of staff. “Just think about it. A municipal agency seeking funding for terrorism-related programs by secret donors. That’s how a municipal city agency does business?” he wrote, calling the Demographics Unit a rogue division of the police force.

In the end, the NYPD acknowledged that it failed to bring up a single case of alleged terrorism with the Demographics Unit, not to mention that the program damaged the relationship between the city’s Muslim population and its governing institutions. “The Demographics Unit created psychological warfare in our community,” said Linda Sarsour, head of the Arab American Association of New York, to the New York Times. “Those documents, they showed where we live. That’s the cafe where I eat. That’s where I pray. That’s where I buy my groceries. They were able to see their entire lives on those maps. And it completely messed with the psyche of the community.”

The city’s new administration, under Bill de Blasio, has charted a different course with its Muslim residents. The unit was disbanded by Police Commissioner Bill Bratton in April 2014 following several months of inactivity that began after de Blasio took office. The officers involved in the unit were reportedly reassigned to other departments. Former Commissioner Kelly has continued to play word games with the mission of what is perhaps his most infamous legacy, insisting that the program was perfectly legal and designed only to know where certain groups of people lived — even though the U.S. Census Bureau already does that.

If Kelly still thinks unwarranted surveillance of Muslim citizens was worth alienating an entire group of innocent Americans, he should endorse Ted Cruz.