John Cooper was a corrupt financial analyst and domestic abuser who was killed by his brother-in-law, acting on behalf of Cooper's wife.
History
Cooper worked as a financial analyst at Dreisner Investments, and would physically abuse his wife, Leslie, and two children when he came home angry. At some point, Leslie tried seeking divorce, but pulled back for unspecified reasons. During his time at Dreisner, Cooper audited a company named Everson Technologies, though he secretly held shares of the latter and received kickbacks by Everson's executives to make it appear as if the company's stock value was high, even though it was plummeting. Eventually, Everson went bankrupt and at least 20.000 investors lost their life savings as a consequence, including Russell Woods, the husband of Leslie Cooper's sister, Georgina, and John's brother-in-law.
Leslie saw this as an opportunity to get rid of her violent husband. She informed Russell that John knew of the impending bankrupt but didn't warn him for the sole purpose of saving his money, and offered him to kill her husband in exchange for a share of the insurance money. Woods accepted, and he shot down John near a ferry terminal. Russell was arrested by Detectives Briscoe and Green, and ADA Southerlyn managed to uncover Leslie's role in the murder. When she was put on trial for first-degree murder, the jury, in a fit of mercy for the abuse she suffered at the hands of John, acquitted her. (L&O: "Equal Rights")