Why hasn't the DOJ investigated the NYPD's practice of spying on Americans?

In early 2011, Attorney General Eric Holder promised members of Congress that the Justice Department was "actively looking at" the New York Police Department's spying on American Muslims. Now, more than a year later, advocates—and two top Democrats—are still wondering what happened.
"I have patiently waited for the Department of Justice to complete its review of the situation, but it has been nearly two years since the story broke and over a year since the Department of Justice committed to doing a review of NYPD's actions," Rep. Mike Honda (D-Calif), who was detained in an internment camp during World War II, told Mother Jones. Honda said that the Justice Department should "conduct a full investigation, not a simple review, of the NYPD's numerous constitutionally questionable actions immediately."
Muslim advocacy groups have regular interagency meetings with the federal government but have also received no official response on the matter. Nor has Rep. Rush Holt (D-N.J.), who says he "first requested that the department conduct an investigation in response to news reports in September of 2011." Since then, Holt adds, "I have received no substantive updates from the Justice Department, despite many follow-up inquiries. To my knowledge, no investigation has been conducted."
Holder repeatedly promised lawmakers that the Justice Department was considering investigating the spying, telling Honda in February 2012 that the department was "reviewing" letters from members of Congress about the NYPD's actions "to determine what action, if any, we should take." The next month, the attorney general went even further: "Just what I've read in the newspapers is disturbing," Holder told a Senate appropriations subcommittee on March 8, 2012. "There are various components within the Justice Department that are actively looking at these matters."
Members of Congress have pressed Holder on the matter since—including at a private meeting of the Congressional Asian Pacific American Caucus in September 2012. At that event, both Rep. Judy Chu (D-Calif.) and Honda both asked Holder in person about the review. Holder told them it was ongoing. Asked by Mother Jones, a DOJ spokeswoman suggested that the department still hasn't made up its mind, adding that "we cannot comment on matters under review."
The question of whether or not to investigate the NYPD's surveillance activities pits two important Obama administration priorities against each other—its aggressive, often controversial efforts to prevent another terrorist attack on the United States, which have been frequently criticized by civil libertarians, and its reinvigoration of the Justice Department's civil rights division. Since taking office, the special litigation section of the civil rights division has investigated more local police departments for unconstitutional policing than ever before, but never on behalf of American Muslims profiled by law enforcement.
Although Holder referred to the reports of the NYPD's actions as "disturbing," that's not the view of everyone in the Obama administration. CIA Director John Brennan, formerly a top White House counterterrorism adviser, praised the NYPD's surveillance program in April 2012. "I have full confidence that the NYPD is doing things consistent with the law, and it's something that again has been responsible for keeping this city safe over the past decade," Brennan said.
That was at odds with Holder's initial take. "In performing these law enforcement functions, we have to take into account, you know, cost-benefit here," Holder told the House appropriations committee in February 2012. "You do not want to alienate a community, a group of people, so that especially impressionable young people think that their government is against them. And then, you know, the siren song that they hear from people who they can access on the internet becomes something that becomes more persuasive to them."http://www.motherjones.com/politics/2013/04/nypd-muslim-surveillance-justice-department-eric-holder