Washington: Yet another white police officer who shot and killed an unarmed black teenager in March in one of a spate of similar incidents sparking protests around America will not face criminal charges.

Tony Robinson Jr, a 19-year-old black man was fatally shot by white police officer Matt Kenny in Madison, Wisconsin, on March 6, setting off days of protests in the city amid tensions over several such previous incidents. There have been at least 14 major instances of a white policeman shooting dead a black person since 17-year-old Trayvon Martin was fatally shot on Feb 26, 2012 in Sanford, Florida. And in all of them policemen have gone scot-free.

Baltimore, near Washington, which last month erupted in riots and violence last month over the death of Freddie Gray, a 25-year-old black man in police custody, was different from other incidents in that six involved police officers have been charged there.

Dane County District Attorney Ismael Ozanne announced Tuesday that he had concluded “that this tragic and unfortunate death was the result of a lawful use of deadly police force and that no charges should be brought against Officer Kenny”

While the Wisconsin Professional Police Association welcomed the decision not to charge Kenny, it drew swift criticism from several of Robinson’s family members with his grandmother, Sharon Irwin saying “This is politics, and not justice.”

Robinson’s mother Andrea Irwin said her family “absolutely” plans to file a civil lawsuit against the Police Department and alleged: “They have done a smear campaign against my child and against me since this all began.”

Robinson’s family has hired a Chicago law firm to carry out its own investigation into the shooting and commissioned a private autopsy, according to the Wisconsin State Journal.

Attorney Jon Loevy said Robinson’s family supports protests over the case, but stresses they should not be violent.

Near the site of the March shooting, demonstrators held a large banner Tuesday that said, “BLACK LIVES MATTER” and chanted, “No justice, no peace, no racist police.”

Noting his own background as the first district attorney of colour in the state, Ozanne told reporters: “My decision will not bring Tony Robinson Jr. back.”

“My decision will not end the racial disparities that exist in the justice system, in our justice system,” he was quoted as saying by CNN.

“My decision is not based on emotion. Rather, this decision is based on the facts as they have been investigated and reported to me.”

Ozanne said txicology reports confirmed that Robinson had taken hallucinogenic mushrooms, marijuana and Xanax before the shooting and 911 calls reported that he was acting “insane” and attacking people.

Kenny who called to an apartment over reports that Robinson had been jumping in front of cars and assaulting people, claimed that Robinson hit him and knocked him into the wall inside the apartment.

After that, Kenny said he was afraid Robinson would hit him again or take his gun, and opened fire as the 19-year-old continued to come at him.

In three seconds, seven shots were fired. All of them hit Robinson at close range, Ozanne said.

Kenny has been on paid administrative leave since the shooting. That status will continue, the police chief said Tuesday, while the department completes an internal policy review of the incident.

The Police Department has said it prepared for the prosecutor’s announcement for weeks and hoped to avoid violence and property damage.