NEWARK, N.J. (AP) — The Department of Justice announced Monday an investigation into allegations of excessive force, discriminatory policing and other violations by the police department of New Jersey’s largest city.

The move comes eight months after the state American Civil Liberties Union complained of rampant misconduct and lax internal oversight in the Newark Police Department, though federal and city officials said the ACLU’s petition wasn’t the main reason for the probe.

U.S. Attorney Paul Fishman said justice officials will also look into allegations of poor treatment of detainees in holding cells and will investigate whether officers have retaliated against those who legally observe, or record, police activity.

“Our goal remains the same, to ensure that the people of Newark are served by a police force that effectively fights crimes and enjoys the confidence and respect of the community it serves,” he said.

Newark has long been one of the most violent and poorest cities in New Jersey. Its violent crime rate fell dramatically in 2008 and 2009, but has inched upward in the past two years. The city, which has about 280,000 residents, recorded 28 murders through the end of April, a 65 percent increase over the same period a year ago.

The city laid off more than 160 police officers at the end of last year to close a budget gap, marking the city’s largest force reduction in 32 years. Last week, incoming Chicago Mayor Rahm Emanuel announced that Newark Police Director Garry McCarthy was his pick to be police superintendent of the nation’s third-largest city.

Justice officials will work with members of the police department, city officials, community leaders, civil rights groups and civilians to determine “whether there are systemic violations of the constitution or federal law” by the Newark Police Department, Fishman said. A report of the findings will be made public, he added, though no time frame was given.

In a 96-page filing to the DOJ in September, the ACLU called for federal oversight of the city’s police department. The ACLU filing cited 418 instances of misconduct that included officers breaking a man’s jaw and eye socket during an arrest and seven deaths attributed to Newark officers that included shootings or ignoring urgent health complaints.

The organization said that out of 261 complaints filed with the police department’s internal affairs division from 2008 to 2009, only one complaint, alleging an improper search, was found credible. It said the city had paid $4.8 million over 2 1/2 years to settle 38 cases brought against police by residents or department employees, with at least three dozen lawsuits pending.

“The announcement that the DOJ will bring its resources and expertise to our city and hold the NPD accountable marks a critical moment in our city’s history,” said Deborah Jacobs, executive director of ACLU’s New Jersey chapter. “The cries of Newarkers have finally been heard.”

Jacobs added that the ACLU had been calling for federal intervention in the department since 1967.

Newark police and city officials, including Mayor Cory Booker, had called some of the ACLU’s allegations frivolous and inaccurate when the petition was filed, arguing that the group skewed the data and exaggerated problems.

McCarthy said he had implemented several reforms in the department since taking over in 2006, including an agencywide performance monitoring system, new compliance and integrity tests to ensure that complaints were properly received and processed by the department, and revamping the internal affairs division.

Of 26 civilian lawsuits against the police that were cited by the ACLU in its petition, more than two-thirds of the incidents predated McCarthy’s tenure.

Deputy Chief Samuel DeMaio, a longtime law enforcement officer in the city, has been named acting police director in Newark as McCarthy announced he was stepping down after being selected by Chicago Mayor Rahm Emanuel to be the new police superintendent in the nation’s third-largest city.

Emanuel’s team said in a statement Monday that McCarthy instituted “aggressive and successful reforms” during his tenure in Newark. They also said McCarthy asked the DOJ to work with Newark to study its reforms.

Assistant Attorney General for the Civil Rights Division of the DOJ, Thomas Perez, said Monday that the information leading to the investigation had come from a variety of sources and had not been prompted by one single event.

Police officials said they welcomed the probe. Detective James Stewart, Jr., vice president of the Fraternal Order of Police Lodge No. 12 in Newark, said they were cooperating with the investigation, but that oversight of the police, and department regulations, were more stringent than ever.

“If anything, there is excessive discipline in this department,” Stewart said. “The perception that we run around out there and do whatever we want to is completely untrue.”

Booker, who criticized the ACLU’s original petition by saying its recommendation of bringing federal oversight to the police department was too drastic a step, said he viewed the DOJ investigation as a form of additional federal help in dealing with the city’s crime problem.

“It’s an opportunity that has nothing but a win-win scenario for us,” Booker said. “I’m grateful we’re announcing a process that we started months ago. I think the accomplishment will help us meet the goals for the department we’ve already set.”

The DOJ has done similar reviews of law enforcement agencies in New York, Ohio, Washington, Pennsylvania, Washington, D.C., Louisiana and California.

Fishman said he and Perez would also be meeting Monday with community groups, civil rights organizations, Arab-American and Muslim community leaders and members of the police department to discuss policing and civil rights concerns.

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Associated Press writers Deanna Bellandi in Chicago and David Porter in Newark, N.J., contributed to this report.

Copyright 2011 The Associated Press.