ENNIS, Texas (CBSDFW.COM) – Two top city leaders are out of their jobs in Ennis after an investigation by special prosecutors raised questions about police investigations in the city.

City Manager Scott Dixon resigned and Police Chief John Erisman retired Friday.

A statement from Mayor Angie Juenemann cited “recent concerns… regarding the operation and oversight of our police department.”

CBS 11 has learned the Ellis County District Attorney’s Office earlier this year temporarily paused cases from the Ennis Police Department, holding off trials and plea deals. Several cases, which depended solely on the testimony of an officer and had no clear victim, were dismissed altogether after prosecutors lost confidence in the department’s competence and credibility.

A report obtained by CBS 11 details a recent investigation into issues at the department prompted by a 2016 aggravated robbery at a Chipotle restaurant in Ennis.

“Oh, it was a horrible, scary crime,” said Ellis County District Attorney Patrick Wilson. “Masked gunmen came in the back door and violently robbed the place and pistol whipped an employee.”

In 2018, Ennis Police were finally able to identify two suspects through a DNA hit, but Wilson said prosecutors discovered problems with the evidence.

“It’s my office’s belief in this case that this case cannot prosecuted because of the poor police work,” said Wilson.

The grand jury examining the case turned its attention from the accused robbers to the police department’s actions, taking the unusual step of requesting to extend their term.

“In my entire career, I’d never seen this before,” said Wilson.

In August, the district attorney brought on special prosecutors to conduct an independent review of the case and the grand jury proceedings.

“No Ennis PD officer could credibly explain who discovered several key pieces of evidence,” they wrote in their report.

The district attorney said among the key evidence was DNA, shell casings and firearms.

“We need to know specifically where were they found, who gathered them, who put them in a pile for the photograph. Those questions couldn’t be answered,” he said.

The investigation found a crime scene investigator didn’t have enough evidence markers.

“So he simply used the few… available to him,” read the prosecutors’ report.

Even more surprising to those reviewing the case was an absence of detail about an exchange of gunfire, in which an officer fired shots at fleeing suspects.

“There were officers on scene who wrote reports, and if you read their reports, you would have no idea a shooting took place there. None,” said Wilson. “It’s shocking and appalling and extraordinary, to say the least.”

Wilson expressed hope recent changes in leadership would result in a better police department for Ennis residents.

“They deserve professionalism, they deserve integrity, they deserve competence and I think they’re going to get it as a result of this,” said Wilson.

Attempts to reach former Police Chief John Erisman for comment were unsuccessful.

Below is the special prosecutors report on the Ennis Police Department’s operations: