BLACK rights activists vowed at the weekend to intensify the struggle for political change after the killer of 17-year-old black man Laquan McDonald received just six years and nine months in jail.

Former Chicago police officer Jason Van Dyke’s conviction for second-degree murder last October was seen as a victory by Black Lives Matter activists, as it was the first time in half a century that a police officer in the city had been convicted for killing someone while on duty, although family and campaigners said that he should have been found guilty of the stronger charge of first-degree murder.

Mr Van Dyke’s argument that Mr McDonald had been aggressively swinging a knife at him when he fired at him in 2014 was disproved by dash-cam footage released the next year, which showed the officer firing 16 rounds into the teenager’s back as he walked away.

Activist William Calloway said the black community was “heartbroken” by a sentence which could see Mr Van Dyke released after just three years, but vowed to campaign for change at the ballot box.

And the decision comes just days after three officers were cleared of conspiring to cover up the truth about the killing to protect Mr Van Dyke.

Former detective David March, former officer Joseph Walsh and suspended officer Thomas Gaffney were found not guilty after Judge Domenica Stephenson said there was not enough evidence to prove conspiracy.

The three had supplied statements backing up Mr Van Dyke’s account of the murder which were similarly proven false by the dash-cam footage. 

Ms Stephenson said it would be “unfair” to compare the officers’ reports on the incident to video footage of it, as that would be to apply “the benefit of hindsight.” And she added: “McDonald was an armed offender who ignored commands to drop the knife.”

Mr McDonald’s great uncle the Reverend Martin Hunter said the acquittals were “not justice” and condemned the short prison sentence for the officer who murdered his nephew.

But he said any jail sentence meant progress. “If they’d sentenced him to one minute it’s a victory. It sends a strong message to unjust police officers that you can go to jail if you’re caught lying.”