LAPD Chief Charlie Beck (Creative Commons)

Prior to Officer Mary O'Callaghan's initial arraignment, the Los Angeles Police Department Chief responded Thursday to the charges filed. 

"Our detectives worked closely with the District Attorney's Office on preparing and filing this case," said Police Chief Charlie Beck. "The officer's actions that day, as seen on the video, did not meet the expectations I have of our officers in the field."

A Police Commission investigation revealed video evidence of O'Callaghan kicking Alesia Thomas, 35, multiple times in the abdomen, groin and upper thigh as she was entering the back of a police car.

Thomas was pronounced dead at a hospital just a few hours after officers arrested her at her South Los Angeles apartment on suspicion of abandoning her two young children at a police station. 

According to a report by the Police Commission, Thomas had cocaine in her system at the time of the arrest and fought back, kicking and screaming when O’Callaghan took her into custody. 

In a district attorney’s office press release, prosecutors reported insufficient evidence as the reason why O’Callaghan is charged with assault as opposed to involuntary manslaughter. 

O'Callaghan was one of multiple officers present for the arrest, but her actions were the only ones thought to violate LAPD policies, the report says.  

“As troubling as this case is, it demonstrates that our system of discovering misconduct is working, and that we will hold our officers accountable for their actions,” Beck said. 

O’Callaghan pled not guilty on Tuesday to a felony count of assault by a public officer with a maximum sentence of three years in prison and will remain free until her next court appearance. 

Reach Staff Reporter McKenna Aiello here, and follow her on Twitter @McKennaAiello.