The Justice Department cleared officer Darren Wilson in a Ferguson, Mo., civil rights probe, but in a separate report, the agency accused the police department of bias and cited offensive e-mails. (The Washington Post)

The Justice Department on Wednesday released a report explaining why it will not pursue federal civil rights charges against Darren Wilson, the white police officer, who shot and killed Michael Brown, an unarmed black 18-year-old, in Ferguson, Mo., last August.

The department found that Wilson’s actions “do not constitute a prosecutable violation” and there “is no evidence upon which prosecutors can rely to disprove Wilson’s stated subjective belief that he feared for his safety.”

[Read: The DOJ report on the police department in Ferguson]

In a second report on broader police practices, the Justice Department released seven racist e-mails written by Ferguson police and municipal court officials. A November 2008 e-mail, for instance, stated that President Obama could not be president for very long because “what black man holds a steady job for four years.” Another e-mail described Obama as a chimpanzee. An e-mail from 2011 showed a photo of a bare chested group of dancing women apparently in Africa with the caption, “Michelle Obama’s High School Reunion.”

The Justice Department did not specifically identify who wrote the e-mails and to whom they were sent, but said they were written by police ad court supervisors who are currently employed by the city.

Attorney General Eric H. Holder Jr. detailed the findings of a civil rights investigation into the Ferguson, Mo., police department, saying there is an "implicit and explicit racial bias" that accounts for the hostile relations between law enforcement and residents. (AP)

The second report accused the police department in Ferguson, Mo., of racial bias and routinely violating the constitutional rights of black citizens by stopping drivers without reasonable suspicion, making arrests without probable cause and using excessive force, officials said.

Federal officials opened their civil rights investigation into the Ferguson police department after the uproar in the St. Louis suburb and across the country over the fatal shooting of Brown last year. A grand jury in St. Louis declined to indict Wilson in November.

[The seven racist e-mails the Justice Department highlighted in its report on Ferguson police]

Although federal officials will not bring civil rights charges against Wilson, they see their broad civil rights investigation into the troubled Ferguson police department as the way to force significant changes in Ferguson policing.

“As detailed in our report, this investigation found a community that was deeply polarized, and where deep distrust and hostility often characterized interactions between police and area residents,” said Attorney General Eric H. Holder Jr. “Our investigation showed that Ferguson police officers routinely violate the Fourth Amendment in stopping people without reasonable suspicion, arresting them without probable cause, and using unreasonable force against them. Now that our investigation has reached its conclusion, it is time for Ferguson’s leaders to take immediate, wholesale and structural corrective action. The report we have issued and the steps we have taken are only the beginning of a necessarily resource-intensive and inclusive process to promote reconciliation, to reduce and eliminate bias, and to bridge gaps and build understanding.”

Holder is expected to speak about the reports Wednesday afternoon.

In hundreds of interviews and in a broad review of more than 35,000 pages of Ferguson police records and other documents, Justice Department officials found that although African Americans make up 67 percent of the population in Ferguson, they accounted for 93 percent of all arrests between 2012 and 2014.

The Justice Department investigation of the Ferguson Police Department

Benjamin Crump, the attorney for Brown’s family, said the report into police practices confirms “what Michael Brown’s family has believed all along, and that is that the tragic killing of their unarmed teenage son was part of a systemic pattern of policing of African American citizens in Ferguson.”

[Read: Department of Justice report on the Michael Brown shooting]

The findings come as Justice Department officials negotiate a settlement with the police department to change its practices. If they are unable to reach an agreement, the Justice Department could bring a lawsuit, as it has done against law enforcement agencies in other jurisdictions in recent years. A U.S. official said that Ferguson officials have been cooperating.

As part of its findings, the Justice Department concluded that African Americans accounted for 85 percent of all drivers stopped by Ferguson police officers and 90 percent of all citations issued.

The review concludes that racial bias and a focus on generating revenue over public safety have a profound effect on Ferguson police and court practices and routinely violate the Constitution and federal law.

“We owe it, not just to law enforcement, but to Michael Brown, Tamir Rice and Eric Garner to figure out what’s really going on here so it can be addressed,” said Jeff Roorda, a former Missouri state representative and a spokesman for the St. Louis Police Officers Association, referring to others killed by police officers in Cleveland and New York. “Reaching conclusions from statistics about traffic stops I don’t think draws the whole picture.”

The Justice review also found a pattern or practice of Ferguson police using unreasonable force against citizens. In 88 percent of the cases in which the department used force, it was against African Americans.

In Ferguson court cases, African Americans are 68 percent less likely than others to have their cases dismissed by a municipal judge, according to the Justice review. In 2013, African Americans accounted for 92 percent of cases in which an arrest warrant was issued.

Justice investigators also reviewed types of arrests and the treatment of detainees in the city jail by Ferguson police officers. They found that from April to September 2014, 95 percent of people held longer than two days were black. The police department also overwhelmingly charges African Americans with certain petty offenses, the investigation concluded.

For example, from 2011 to 2013, African Americans accounted for 95 percent of all “manner of walking in roadway” charges, 94 percent of all “failure to comply” charges and 92 percent of all “peace disturbance” charges, the review found.

The shooting of Brown on a Ferguson street on Aug. 9 set off days of often violent clashes between demonstrators and police in the streets of Ferguson.

Elected officials, protest organizers and community leaders renewed calls Tuesday for Ferguson Police Chief Thomas Jackson to resign — some adding that the department should be disbanded — and said the Justice Department probe should have gone further by investigating other municipal police forces in the area.

“I would speculate that the same pattern and practices of Ferguson exist in every other department in St. Louis County,” said Adolphus Pruitt, the president of the St. Louis NAACP, which has filed racial discrimination complaints against county police.

[DOJ report renews outrage in Ferguson]

He added, “It’s time for the Ferguson police department to disappear.”

Justice Department investigators spent about 100 days in Ferguson, observing police and court practices, including four sessions of the Ferguson Municipal Court. They conducted an analysis of police data on stops, searches and arrests, as well as data collected by the court, and met with neighborhood associations and advocacy groups. The investigators also interviewed city, police and court officials, including the Ferguson police chief and his command staff.

In the past five years, the Justice Department’s civil rights division has opened more than 20 investigations of police departments, more than twice as many as were opened in the previous five.

The department has entered into 15 agreements with law enforcement agencies, including consent decrees with nine of them, including the New Orleans and Albuquerque police departments.

Kimberly Kindy, Sarah Larimer and Wesley Lowery contributed to this report.