Image copyright Getty Images

The Chicago Police Board has fired four officers for allegedly covering up the 2014 fatal police shooting of black teenager Laquan McDonald.

Sgt Stephen Franko and officers Daphne Sebastian, Janet Mondragon and Ricardo Viramontes were dismissed on Thursday after a vote by the nine-member board.

The board determined the officers had exaggerated the threat level of the 17-year-old to justify the shooting.

Jason Van Dyke, who killed McDonald, was convicted of murder last year.

The police board on Thursday voted unanimously to dismiss three of the officers, with one member dissenting in the decision to fire Ms Sebastian as she was not found to have lied.

The officers may appeal the firings in court.

The four were accused of making false statements about the shooting, which saw Van Dyke fire 16 shots at the teenager in a span of 15 seconds.

Officers Mondragon, Viramontes and Sebastian were all present at the scene of the shooting, and Sgt Franko signed off on their reports, the Chicago Tribune reported.

Ms Mondragon said she did not see the shooting, and Mr Viramontes had reported that the teen tried to get up while holding a knife, despite video evidence showing otherwise. Ms Sebastian was accused of giving investigators inconsistent and misleading statements about the incident.

Sgt Franko later claimed to have overlooked the details of the report.

Image copyright Getty Images Image caption Demonstrators celebrated the verdict in the murder trial of Chicago police officer Jason Van Dyke in Chicago last year

The city's Fraternal Order of Police criticised the decision and has maintained the officers did nothing wrong.

The Order's vice-president Patrick Murray told local media in a statement: "It is obvious that this police board has out-served its usefulness."

In January, three other officers involved and accused of lying to protect Van Dyke - David March, Joseph Walsh and Thomas Gaffney - were acquitted by a judge of conspiracy, obstruction of justice and misconduct charges.

After a trial last October, Van Dyke was found guilty of second-degree murder as well as 16 counts - one for each shot he fired - of aggravated battery.

The firings this week are probably the final repercussions to come from the 2014 shooting, local media say.

What's the background?

The shooting sparked protests against police brutality nationwide and led to a federal investigation into the Chicago police department that found a "pervasive cover-up culture". The city's police superintendent was fired following the unrest and the top prosecutor lost a re-election bid.

Police dashcam video from 2014 showed white Officer Jason Van Dyke shooting McDonald 16 times as the 17-year-old walked down the road holding a pocket knife.

According to the Chicago Tribune, which called the verdict "stunning", the case was considered to be the first time in the city's history that police officers have faced criminal charges stemming from an on-duty shooting.

Image copyright Reuters Image caption Jason Van Dyke (pictured) has been found guilty of killing the black teenager

Prosecutors alleged the three officers falsified reports and tried to conceal the events surrounding McDonald's death "to shield their fellow officer from criminal investigation".

"The defendants allegedly lied about what occurred and mischaracterised the video recordings so that independent criminal investigators would not learn the truth about the killing and the public would not see the video recordings," they said when charges were announced in June 2017.