He coached people on how to pass a polygraph test, whether they lied or told the truth. And for it, he was sentenced to two years in prison.

Douglas G. Williams, a 69-year-old former Oklahoma City police officer, was sentenced Tuesday to two years in prison for charges related to his business Polygraph.com.

Through the business, Williams offered one-on-one training sessions to clients so they could “conceal misconduct and other disqualifying information” when taking polygraph tests in connection with federal background checks for employment or other investigations, according to prosecutors who brought charges against him.

Williams had worked for the Oklahoma City Police Department for about a decade, quitting in 1979 after he decided that the polygraphs tests he administered in the department were a fraud. He went on to claim through his website that he could teach anyone to pass such a test “nervous or not — lying or not — no matter what!”

Federal investigators caught wind of Williams‘ business and set up appointments that turned out to be a sting. Two undercover officers posed as posed as law enforcement officers who had committed serious crimes they were trying to cover up — one said he was under investigation for allowing drugs to be smuggled into the United States and another said he had smuggled drugs into a jail as a corrections officer and had sexual contact with a 14-year-old girl in police custody.

“Defendant attempted to teach an admitted drug trafficker to lie to avoid criminal prosecution and keep his job as an Inspector at the airport and to teach an admitted drug dealer and child molester to lie to get a position as a Customs and Border Patrol agent,” prosecutors wrote in sentencing memos, advocating for a jail sentence of 30 months. “The severity and nature of defendant’s conduct, which could have put our country and its citizens at serious risk, sets this case apart from other obstruction of justice and wire fraud cases.”

The trial against Williams had started in May when he reversed course and pleaded guilty to five criminal charges — to two counts of mail fraud and three counts of witness tampering.

Williams‘ attorney asked for probation rather than a prison sentence, noting that other than the offenses his client had pleaded guilty to, he was a law-abiding citizen and had spent much of his life “promoting respect for the law.”

Attorney Stephen Buzin also noted that Williams had taken down the website advertising his services.

“Mr. Williams has taken down the website polygraph.com and stopped the distribution of any materials, manuals and DVD’s formerly offered and associated therewith,” Mr. Buzin wrote.

U.S. District Judge Vicki Miles-LaGrange of the Western District of Oklahoma handed down the two-year sentence.