Charlie Kovac is a plumber and former colleague of Denise Johnson, who hired him to kill her husband Daniel so she wouldn't be financially destitute because of him. When Kovac demanded more of a payment, Denise shot him dead with her boss' gun.
Denise was only tried for Kovac's murder due to the available evidence, but a previous hitman who failed, Dewey Lattimer, was found. Denise pleaded to murder once she heard Lattimer would testify against her. (L&O: "Purple Heart")