(CNN) — Prosecutors in Memphis, Tennessee, will review all cases that involved the five officers charged in the brutal beating death of Tyre Nichols during a traffic stop, the district attorney’s office said, as newly released documents show a sixth officer involved in the encounter lied in his statements to investigators.

“The office will review all prior cases — closed and pending,” Shelby County District Attorney Steven Mulroy said in a statement.

It is unknown how many cases this will involve.

“This is just the beginning,” Erica Williams, the spokeswoman for Mulroy, told CNN. “This involves any criminal case that [the officers] were involved in. It is any case where there were criminal charges that were brought by the DA anytime since they became officers.”

The review comes as police documents detail alleged false statements made by Preston Hemphill following Nichols’ death. Hemphill was fired from the Memphis Police Department last week for violating multiple department policies, including personal conduct and truthfulness. He was the sixth officer to be terminated after Nichols’ death.

In his statement on a form regarding the incident, Hemphill said Nichols attempted to grab his partner’s duty weapon. The statement was part of a decertification letter Memphis Police sent to the Tennessee Peace Officer Standards and Training Commission (POST).

“There is no video footage to corroborate that statement,” the document said, adding that Hemphill then provided a conflicting statement to investigators, telling them he “did not see the subject grab your partner’s gun.”

Hemphill was seen on his body cam video tasing Nichols and later heard saying, “I hope they stomp his ass.” While on top of Nichols, Hemphill “used the assaultive statement, ‘Get on the f**king ground. Finna tase yo ass,'” according to a police document obtained by CNN Thursday.

The January release of video of Nichols, 29, being repeatedly punched and kicked by police shook a nation long accustomed to videos of police brutality — especially against people of color.

Nichols died in a hospital days after the beating.

Earlier this week, letters of decertification for five other officers, who have been charged in Nichols’ death, stated that those officers’ accounts were “not consistent with each other and are not consistent with the publicly known injuries and death of Mr. Nichols,” the documents say.

Hemphill also said in a statement that Nichols was stopped for “driving recklessly at a high rate of speed,” but then acknowledged that he “did not witness the subject driving in such a manner,” the document said.

“You stated that you and your partners stopped the driver and attempted to detain him, and he began to resist,” the decertification letter reads.

“You stated that after he stood up from being on the ground, he started fighting with you and your partner, at which time you deployed your city-issued taser. The video evidence does not corroborate your statement,” it continued.

“Video evidence shows the subject was not resisting but was running away from you while you attempted to tase him,” it said.

Hemphill was given the opportunity to review his version and told investigators that the details were correct, the document said.

“Your statements were inconsistent and untruthful, and you documented false statements,” it added.

If the decertification is granted by the state, it would prohibit Hemphill from working for other state law enforcement agencies.

Lee Gerald, an attorney for Hemphill, said he and his client still disagree with his job termination, but they are cooperating with the investigation.

“Regardless of what the Memphis Police department and the commission decided to do regarding his possible decertification, Mr. Hemphill will continue to cooperate with authorities in the investigation into the death of Tyre Nichols,” Gerald told CNN.

Hemphill has not been criminally charged in the case. The other five terminated officers are due to be arraigned next week on seven counts each, including second-degree murder, aggravated assault, aggravated kidnapping with bodily injury, aggravated kidnapping in possession of a deadly weapon, official misconduct and official oppression, according to the district attorney.

All five officers — Demetrius Haley, Tadarrius Bean, Emmitt Martin III, Justin Smith, and Desmond Mills Jr. — also were internally charged with violating the department’s policies on personal conduct, neglect of duty, excessive or unnecessary force and use of body-worn cameras, according to internal police documents. The charges are not criminal in nature.

Several of the fired officers had received written reprimands or short suspensions for violating policies during their time with the department, personnel files show.

Haley was involved in a November 2021 incident where another officer received a sustained complaint for “excessive/unnecessary force” after a female suspect suffered a dislocated shoulder. Haley didn’t face a departmental charge for force but was reprimanded for failing to document his role in the detention.

Mills received a reprimand in 2019 for not filing a form after the use of physical force against a suspect. Mills used force to take the woman “to the ground so that she could be handcuffed,” according to the summary of his hearing.

While four officers had policy violations, Bean had no written reprimands in the files reviewed by CNN.

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