Williams is accused of having sex with a 14-year-old girl in 1995 while serving as an officer in Kermit, Texas--near Odessa.
The victim's family opted against pressing charges in the case but Williams was forced to resign from the police department and his peace officers license was permanently revoked.
Williams lied about his past on his application with the Brownfield Police Department when he didn't disclose his prior revocation and told the department he was first-time licensee.
Those lies could create a problem if Williams were to testify as an investigating officer at a criminal trial.
"All of the allegations brought up against him about his [peace officer's] license, about his time in Kermit, I believe would be fair game if we went to trial," Lubbock defense attorney Laurie Key explained.
Key was recently appointed as a special prosecutor on a criminal case in Terry County where Williams was the lead investigator.
Key said she was forced to drop the charges after learning about the allegations surrounding Williams about his past.
"A juror could look at that and go 'you know, if he didn't tell the truth then is he telling us about the truth in this case?'" she said.
Williams envoked his 5th Amendment right against self-incrimination at a hearing last Thursday that challenged his questionable past.
Key said if he did that when a defense attorney asked him about his past during a criminal trial, the prosecution's case could be called into doubt.
As a result, Key said she thinks every case Williams has ever investigated should be dismissed.
"It's thrown the whole justice system over there into chaos, I think," she said.
In fact, these new revelations should prompt more questions than answers according to Key.
"How many people have been convicted on Mr. Williams word? How many people would not be sitting in prison today if the jurors had known about Mr Williams at that time?" she asked.