Chief Jon Belmar of the St. Louis County Police Department speaks to demonstrators during a peaceful protest in Ferguson, Mo., on Aug. 23. (Michael B. Thomas/AFP/Getty Images)

St. Louis County Police Chief Jon Belmar said Thursday that he welcomed a collaborative review process with the Department of Justice following days of unrest in Ferguson, Mo.

“I invited this,” Belmar said. “I wasn’t compelled to do it. It’s a collaboration.”

Belmar said officials will take a closer look at the county’s training, bias-free policing policies, traffic stop numbers and the action law enforcement officials took in the days that followed the death of Michael Brown, a black teenager who was shot and killed by Ferguson police officer Darren Wilson on Aug. 9.

“We’re not afraid to have outside reviewers in here,” Belmar said.

Earlier in the day, Attorney General Eric H. Holder Jr. announced plans for a federal investigation into the Ferguson police department, which would address concerns about the use of excessive force and racial profiling. Belmar called the county’s effort “a little different” from Ferguson’s investigation, stressing the voluntary nature of the review.

“It’s not going to be something that’s going to last three weeks,” Belmar said. “It’s something that could potentially last a year to 18 months.”

The killing of Brown, who was unarmed at the time of the shooting, led to demonstrations in the St. Louis area, and law enforcement officials were widely criticized for their response to the protests.

The Washington Post has reported that at least five Ferguson officers have been named in civil rights lawsuits, which claim police used excessive force — including one instance in which a child was allegedly hog-tied.