CLAYTON COUNTY, Ga. -- Channel 2 Action News investigative reporter Mark Winne has obtained a letter from Clayton County Police Chief Tim Robinson detailing shocking allegations of inappropriate conduct from four officers.

The officers are accused of not reporting corruption, supplying drugs at illegal sex parties and even having sex on the job. The letter follows a three-month internal investigation that the police union calls flawed.

“Unfortunately this morning, we had four officers that were terminated,” said Clayton County police spokesperson Lt. Tina Daniel.

“The very culture of the Clayton County Police Department that allowed this behavior to exist must be purged, and replaced with the core values of honor, courage, integrity and commitment,” said Robinson in a memo to county chief of staff Alex Cohillas.

“We did partner with the GBI and the FBI on this, and there was some very damning information,” said Daniel.

Records said Detective Jerald Parks allegedly participated in sex parties and provided drugs to participants and was accused of intentionally botching a kidnapping investigation for personal reasons.

Late Monday afternoon, a union official said Parks went to no sex parties, never provided drugs and didn't party with the other accused officers.

In Officer Lonon Norwood's case, a document stated that a polygraph examiner's opinion was deception was indicated when Norwood denied selling any illegal drugs since he's been a Clayton County police officer. He's also accused of being untruthful about paying for a hotel room for a woman and her sisters.

A memo stated that Sgt. David Robinson failed to take corrective action as a supervisor and admitted to having sex on duty.

It indicates Sgt. Willie Holliday has been accused of failing to report or take action on information regarding police corruption ... and that he admitted "he witnessed two incidents of excessive force but took no action."

“There are many, many officers that work hard every day, put their lives on the line with great integrity and courage and then to have something like this happen …it’s just a very sad day,” said Daniel.

International Brotherhood of Police Officers lawyer Kliff Grimes says at least three of the officers are IBPO members and from what he knows the investigation is flawed. Grimes said the officers maintain their innocence and will fight to keep their jobs.