Police who purposely lose 6 witnesses information and contact info, and the officer also discarded security cam footage himself. Is that misconduct?

My husband was involved in a serious hit and ruin accident on June 12th, 2018. The truck that left the scene of the accident came out of a well known neighborhood for Police and people who are middle class to upper class. Before my husband was taken to the emergency room for numerous injuries a state trooper and two sheriff's deputies were on scene. My phone call with my husband was ALL recorded. At the scene were 6 witnesses. 3 which lived close by who ran out to help my husband and 3 others who stopped and turned around to give police their statements about the truck AND what they saw. The first trooper on scene wasn't the trooper assigned to my husband's case, But was another one (yet they deny that there was ever ANOTHER trooper on scene). There was also security camera footage of the truck running the stop sign, the accident, and then the truck leaving the scene of the accident. The trooper decided that it was "irrelevant" and discarded of it. Is this police misconduct?