The New York City Police Department is disbanding a controversial spying unit that targeted Muslim communities. The so-called Demographics Unit secretly infiltrated Muslim student groups, sent informants into mosques, eavesdropped on conversations in restaurants, barber shops and gyms, and built a vast database of information. But after years of collecting information, it failed to yield a single terrorism investigation or even a single lead. The program was established with help from the CIA, which is barred from domestic spying. In a joint statement, the groups Muslim Advocates and the Center for Constitutional Rights called the decision a “long overdue first step,” saying: “What has to stop is the practice of suspicion-less surveillance of Muslim communities, not just the unit assigned to do it.”