Story highlights Ronald Johnson was shot and killed by Chicago police in October last year

His family wants the dashcam video of the shooting made available to the public

Chicago police have not responded to a request for comment on the case

(CNN) The family of Ronald Johnson is angry and wants answers from the Chicago Police Department.

Johnson, 25, was shot and killed by an officer in October 2014. According to a preliminary police statement released the same day as the shooting, he pointed a weapon at pursuing officers, after first attempting to flee on foot.

But Johnson's family does not believe the official account.

Johnson and his mother

His mother says dashcam footage of the shooting proves her son was murdered, and is pushing for the video's release to the public.

"This got to stop. Y'all covering up this murder. It's been over a year now that my son been murdered and y'all still haven't did y'all job to convict this cop of murder. Shouldn't nobody have to go through this pain over their kids," Dorothy Holmes told reporters Tuesday.

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