PITTSBURG, Calif. (KRON) — Contra Costa County prosecutors dropped criminal charges this week in 40 cases because the police officers behind the investigations can’t be trusted.

“I can confirm that 40 cases have been dropped,” District Attorney’s Office spokesperson Ted Asregadoo said.

Chief Assistant District Attorney Simon O’Connell told KRON4 on Friday that an investigation into multiple police officers’ conduct is still ongoing. The probe is looking into whether “moral turpitude” was committed by officers who serve on the Antioch and Pittsburg police forces.

O’Connell told KRON4, “There are multiple officers who are subjects of an ongoing criminal investigation involving a range of offences which constitute crimes of moral turpitude. The Contra Costa District Attorney’s Office is actively engaged in evaluating these cases to determine whether the charged case is compromised or whether the case can proceed. Community safety remains paramount, and the District Attorney’s Office remains steadfast in preserving as many cases as possible.”

The District Attorney’s Office did not identify any of the officers who are under investigation, nor specify which cases were dropped due to the officers’ lack of credibility.

What is moral turpitude?

“Moral turpitude” is a legal term used for describing, “wicked, deviant behavior constituting an immoral, unethical, or unjust departure from ordinary social standards such that it would shock a community,” according to Cornell Law School’s Legal Information Institute.

For criminal trials, a police department’s lead investigator who worked on the case is routinely called in by prosecutors to testify in front of a jury. If the police officer is considered immoral and lacks credibility, however, the officer’s testimony becomes very problematic in the eyes of the law. Securing a guilty verdict without a credible officer’s testimony is difficult for prosecutors.

In March, the FBI and the Contra Costa County District Attorney’s Office launched a joint probe into officers from the Antioch Police Department and the Pittsburgh Police Department for a broad range of offenses.

According to PPD, “The investigation involves several local police officers, including three current Pittsburg Police Officers. Anytime there is any allegation of criminal misconduct, that is something our organization takes extremely seriously.”

At least three officers were put on paid administrative leave after they were interviewed by FBI agents.

This breaking news story will be updated.

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