(CNN) A Chicago police officer who shot and killed an innocent bystander in 2012 has resigned days before a departmental hearing that could have resulted in his firing.
Dante Servin's resignation Tuesday came months after Chicago's former top cop and Mayor Rahm Emanuel called for his dismissal following a civilian-led inquiry that filed termination charges against him with the city's police board. The board was to determine his fate on Thursday.
Servin's unraveling began in March 2012, when he shot and killed Rekia Boyd, 22, as she walked with a group of people in a park near her home.
Servin, who was off dury, confronted the group and told them to be quiet, police said. Words were exchanged and, as Boyd and the others turned to walk away, Servin fired five shots from his car. Boyd was struck in the head and killed.
"Officer Servin's full actions resulted in termination charges and an unthinkable loss for a Chicago family," interim Police Superintendent Eddie Johnson said in a statement.
"On behalf of the CPD, I extend my deepest condolences to the family of Rekia Boyd and reaffirm this Department's commitment to the highest levels of professional standards by policing and holding ourselves accountable for wrongdoing."
An independent department investigation filed termination charges in November, saying Servin was negligent, violated policy and demonstrated "incredibly poor judgment" by intervening in a citizen dispute while off-duty.
The department said Servin's official status will be "resigned under investigation."
In November, Emanuel said Servin "does not deserve to wear a police star or to patrol our communities."
Chicago's Independent Police Review Authority found that Servin violated the department's deadly force policy and made conflicting statements to investigators, according to CNN affiliate WLS. It also found that Servin had failed to qualify to use the weapon he fired on the night of the shooting.
After the shooting, Servin told investigators that said he feared for his life and fired in self-defense. He claimed he saw Boyd's boyfriend pull a gun from his pants and take aim. No gun was recovered.
Servin was criminally charged with involuntary manslaughter, reckless discharge of a firearm and reckless conduct. He was acquitted in April.