The U.S. Department of Justice has officially added the death of black Staten Island man Eric Garner to its list of ongoing investigations. Outgoing Attorney General Eric Holder and AG nominee Loretta Lynch announced the probe Wednesday night after a grand jury chose not to indict white police officer Daniel Pantaleo for putting Garner in a fatal chokehold this past July. 

The Justice Department is also looking into Michael Brown's death in early August in Ferguson, Missouri, where a grand jury last week decided white officer Darren Wilson would not face charges for shooting the black 18-year-old. The events in Ferguson and Staten Island may sound similar -- both were cases where a white officer killed a black man -- but the timelines differ, especially when it comes to the DOJ's involvement. It took the DOJ two days to get involved in Ferguson. In Staten Island, it took 139 days and a grand jury decision.

Brown died Aug. 9. The Federal Bureau of Investigation and the Civil Rights Division, both under the DOJ, opened a probe two days later into whether Wilson violated Brown's civil rights. "Aggressively pursuing investigations such as this is critical for preserving trust between law enforcement and the communities they serve,” Holder said in a statement

On Sept. 4, Holder announced a separate investigation into the Ferguson Police Department as a whole. The probe would examine officers other than Wilson and look at cases involving deadly force, arrests and searches from past years, NBC News reported. Holder promised the probe would be rigorous and quick.

Garner was killed in Staten Island on July 17. Holder came out a week later and said the DOJ was "closely monitoring" the situation. He did not announce an investigation despite the Rev. Al Sharpton's public demands for a federal probe, the Wall Street Journal reported. "We cannot just depend — and this is important — on police policy to stop the chokehold," Sharpton said, referencing the move prohibited by New York police in 1993. "We need a federal precedent now. And this case can establish federal precedent as well as get justice for Eric Garner and Eric Garner's family."

The next mention of federal investigation came Aug. 14, when U.S. Reps. Yvette Clark, Hakeem Jeffries and Gregory Meeks of New York held a press conference to ask the DOJ for a probe. They and U.S. Reps. Charles Rangel, Jose Serrano and Nydia Velazquez of New York also sent Holder a letter saying the district attorney couldn't handle the case, the New York Daily News reported. "The family of Eric Garner deserves an independent and impartial investigation," Jeffries told reporters. "The only way for that to happen is for the Department of Justice to step in and get involved."

At a New York University speech on Sept. 23, Holder talked about Ferguson and police brutality but not Garner, the Observer reported. "For far too long, under well-intentioned policies designed to be tough on criminals, our system has perpetuated a destructive cycle of poverty, criminality and incarceration that has trapped countless people and weakened entire communities – particularly communities of color," he said.

Holder announced his resignation two days later, saying he would step down when a successor was confirmed. The same day, a group including Brown's parents, Garner's family, the National Association for the Advancement of Colored People, National Action Network and the National Bar Association held a media event to press for a federal investigation into the Staten Island case.

The next time the DOJ addressed Garner's death was this week, when Holder and Lynch announced the probe Wednesday night. “Our prosecutors will conduct an independent, thorough, fair and expeditious investigation," he said in a statement. "In addition to performing our own investigative work, the Department will conduct a complete review of the material gathered during the local investigation."