D.A. Patrick Keane is a still-employed yet senile lead prosecutor responsible for affirming the wrongful convictions of Carlos Hernandez and Ricardo Torres for the murder of Hernandez' mother and the rape and murder of his sister. The two were suspected of a series of rapes, and retired detective Monte arrested the teens and had Torres rat out Hernandez under duress for wrongful convictions, when their alibi was the two of them are gay and were having a night of passion on a private beach.
Keane stayed in office when his subordinates covered for him regarding his dementia. But when Tim Stanton's rapes continued, the Special Victims Unit met him and realized the truth. Tracking and arresting Stanton, he was arrested on DNA evidence and a positive ID and imprisoned on the murder charges. Keane's senility was used by A.D.A. Carisi to release Hernandez, Torres already dead from being raped in prison and died after his release from AIDS.
It is never specified if Keane was charged or even fired from his position. (SVU: "Murdered at a Bad Address")