Three Chicago police officers were indicted Tuesday on felony charges that they conspired to cover up the actions of a police officer who shot and killed 17-year-old Laquan McDonald, and that the officers lied when they said the black teenager "aggressively" swung a knife at them and tried to get up from the ground still armed after he was shot.

The indictment alleges that one current and two former officers lied about the events of Oct. 20, 2014, when Officer Jason Van Dyke shot McDonald 16 times. the Associated Press reports. Van Dyke is being prosecuted for first-degree murder over the shooting. He has entered a plea of not guilty.

Patricia Brown Holmes — appointed special prosecutor last July to investigate officers at the scene and involved in the investigation of the shooting — said in a news release that the three — David March, Joseph Walsh and Thomas Gaffney — "coordinated their activities to protect each other and other members of the Chicago Police Department," including by filing false police reports, ignoring contrary evidence and not even attempting to interview keys witnesses.

The three are charged with felony counts of obstruction of justice, official misconduct and conspiracy. If convicted, they could serve prison time. The official misconduct charge alone carries a maximum penalty of five years in prison and a $25,000 fine.