Missouri Gov. Jay Nixon (D) on Friday defended his response to the protests and law enforcement action in the town of Ferguson after a police officer shot and killed an unarmed black teenager over the weekend. 

"Monday I asked for a Department of Justice investigation. Monday," Nixon said at a press briefing. "On Tuesday I appeared in the community. On Wednesday I appeared in the community. On Thursday I appeared in the community. On Friday, I'm here — whatever folks are saying out there."

Police have been criticized for their militarized response and for firing rubber bullets and tear gas at demonstrators and members of the media. Nixon was criticized for waiting until Thursday to make a change in security. 

On Thursday, the governor brought in the state Highway Patrol to lead security, helmed by Capt. Ron Johnson, an African-American who is from the community. The shift resulted in zero arrests Thursday night. 

"I think there are a lot of steps along the way that are going to cause angst and pressure," Nixon said. Nixon has criticized law enforcement officers' use of military-style equipment during the protests. 

"That is natural and appropriate. There is a young man who was killed. There is an officer involved in that. There is a great deal of energy — appropriate, accurate, real energy."

Johnson also defended the governor. 

"I can't remember a time when we've had a governor for five days be involved and show up and be here," he said. 

Nixon said the most important task is finding out "how and why" 18-year-old Michael Brown was killed. 

Police on Friday released the name of the officer who was involved in the shooting: six-year veteran Darren Wilson. Police also released new details about an alleged robbery that Brown was involved in minutes before he was killed. 

Nixon said information has to be thorough and complete "before conclusions can be reached."

"New facts are out that weren't out yesterday, but those are not the full picture of anything," he said. "Those are some facts that came out. And I'm not saying they aren't relevant or important."