Or, if it was a "drop gun"......
If that were the case, it would be a good trick with a freeway full of witnesses who never saw what appeared to be gun in the decedents hand. Btw, that area of freeway is jammed with people, and after a collision, everyone would be going real slow and gawking at the parties involved.
In other words, if she exited her vehicle with nothing in her hand which resembled a gun, it would be awful hard to plant one after she was shot dead while alleging she pointing it the cop prior to her being shot. No bueno.