Darren Wilson resigned from the Ferguson Police Department, his lawyer said Saturday, nearly four months after the white police officer’s fatal confrontation with the unarmed Michael Brown sparked protests across the USA.

His resignation is effective immediately, said one of his lawyers, Neil Bruntrager.

“I’m resigning of my own free will,” he told the newspaper in a phone interview. “I’m not willing to let someone else get hurt because of me.”

I, Darren Wilson, hereby resign my commission as a police officer with the City of Ferguson effective immediately. I have been told that my continued employment may put the residents and police officers of the City of Ferguson at risk, which is a circumstance that I cannot allow. For obvious reasons, I wanted to wait until the grand jury made their decision before I officially made my decision to resign. It was my hope to continue in police work, but the safety of other police officers and the community are of paramount importance to me. It is my hope that my resignation will allow the community to heal. I would like to thank all of my supporters and fellow officers throughout this process.

A St. Louis County grand jury has brought no criminal charges against Darren Wilson, a white police officer who fatally shot Michael Brown, an unarmed African-American teenager, more than three months ago in nearby Ferguson.

At a news conference, the St. Louis County prosecutor, Robert P. McCulloch, said that members of the grand jury deliberated for more than two days before finding that no probable cause existed to file charges against Officer Wilson.

The decision set off a new wave of anger among hundreds who gathered outside the Ferguson Police Department. Police in riot gear stood in a line as demonstrators chanted and threw signs and other objects toward them as the news spread. One woman said: “The system failed us again.”

Mr. Brown’s family issued a statement expressing sadness but calling for peaceful protest and a campaign for body cameras on police officers nationwide. “We are profoundly disappointed that the killer of our child will not face the consequence of his actions,” the statement said. “While we understand that many others share our pain, we ask that you channel your frustration in ways that will make a positive change. We need to work together to fix the system that allowed this to happen.”