The white off-duty St. Louis police officer who fatally shot a black teenager last October in a firefight will not face charges in the killing, the local prosecutor's office said on Monday.

The shooting of 18-year-old VonDerrit Myers in a St. Louis neighborhood renewed intensity of demonstrations in the area after unarmed black teenager Michael Brown was shot dead in August by a white police officer in the suburb of Ferguson.

Jennifer Joyce, the City of St. Louis Circuit Attorney, declined to bring criminal charges against the officer saying her office's independent investigation largely tracked with the police account that Myers was armed and fired on the officer before he returned fire in self-defense.

"This is a tragic situation for our entire community, and my thoughts and prayers remain with the Myers family. I know their loss is heartbreaking," Circuit Attorney Joyce said in a statement.

Joyce said prosecutors reviewed an array of evidence, including physical and forensic evidence and witness statements, but were unable to independently interview the officer or three people who were with Myers the night of the Oct. 8 shooting.

Joyce did not name the officer as he had not been charged with a crime, but St. Louis Metropolitan Police Chief Sam Dotson identified him as Jason Flanery in a statement to the St. Louis Post-Dispatch.

A private autopsy conducted for the teen's family said Myers was shot six times in the back of the legs - four of which struck him in the back of the legs consistent with him running up a hill - and once in the side of the head.

Jerryl Christmas, an attorney for the Myers family, told the Post-Dispatch that he intended to file a wrongful death suit over the case.

"I don't believe for a minute that VonDerrit had a weapon," Christmas told the newspaper. "Flanery threw that gun down on him just like they threw that stun gun down on Walter Scott in South Carolina."

Police use of force, particularly against black people and other minority groups, has been under increased scrutiny across the country following the police killings of unarmed black men in cities like Ferguson, New York City, North Charleston, South Carolina and elsewhere over the past year.