Blue Steel (1990)

When rookie cop Megan Turner (Jamie Lee Curtis) kills a convenience store robber, she does not notice when psychopathic commodities trader Eugene Hunt (Ron Silver) takes the dead man's gun. With no weapon at the crime scene, the police hold Turner accountable for killing an unarmed man. Meanwhile, Hunt uses the stolen weapon to go on a killing spree. Turner teams up with detective Nick Mann (Clancy Brown) to clear her name and catch the killer. An unexpected romance complicates matters.