SANTA MARIA, Calif. -

Former Santa Maria Police Lieutenant Dan Ast defended his decision-making in the hours and minutes leading up to the tragic on-duty shooting death of SMPD Officer Albert Covarrubias Jr. in January 2012 by a fellow officer and close friend involved in trying to place him under arrest.

Covarrubias was under investigation for having an unlawful sexual relationship with an underage female SMPD Explorer Scout he was working with.

Covarrubias was confronted by uniformed officers looking to arrest him while he was on duty after working a DUI checkpoint on North Broadway in
Santa Maria in January 2012.

Investigators determined Covarrubias resisted arrest, fired his handgun during a scuffle with the arresting officers, one of whom, his best friend, returned fire killing Covarrubias at the scene.

In his first testimony since his arbitration hearing began earlier this week seeking his job back, Dan Ast said he was following the instructions of his on-duty commander in investigating Officer Covarrubias.

Ast defended the decision to arrest Covarrubias while he was on-duty at the end of his late-night shift in the field.

But Ast said the investigation and arrest spiraled quickly out of control the night of the deadly shooting after Covarrubias learned he was being investigated for having unlawful sex with an underage girl and would be arrested, and then became suicidal.

Dan Ast was fired by Santa Maria Police Chief Ralph Martin following an internal police department investigation into the shooting death of Officer Covarrubias.

Under steady questioning by the attorney representing the City of Santa Maria in Ast's arbitration hearing to get his job back, the law enforcement veteran defended how he and his fellow officers pursued Officer Covarrubias leading up to the night and the hour of the deadly shooting.

The arbitration hearing for former SMPD Lieutenant Dan Ast is expected to wrap up at the end of the week.

It could be several weeks before the arbitration hearing officer makes a recommendation to the Santa Maria City Manager who will have the ultimate say on whether or not Dan Ast gets his job back.