ARVADA, Colo. -- Arvada Police Chief Don Wick issued a statement Friday afternoon and answered questions regarding an investigation in an excessive force case that resulted in the resignations of four officers and the suspension of two others.

On Thursday, police announced that two officers were placed on paid administrative leave pending the outcome of an internal investigation looking into allegations of inappropriate conduct by members of the department.

On Friday, Wick said the fourth officer had submitted his resignation as part of the probe. Two others resigned earlier in connection with separate internal personnel matters not directly related to the assault, police said.

"There are allegations of misconduct by officers lying to their supervisor, lying in an official police report either directly or thru omission and laying in an investigative proceeding. This behavior cannot and will not be tolerated," Wick said.

"One focus of the investigation is an allegation that an officer assaulted a suspect in January. In addition, an allegation was made that one or more officers witnessed the incident and failed to report it to their superiors, according to the police department," Wick said.

The Arapahoe County Sheriff’s Office has been asked to conduct a simultaneous investigation to determine if any criminal charges should be filed in the matter.

"If charges are appropriate, I'm confident the sheriff's office will file those charges," Wick said.

He said he was limited in what he could release to the public because the investigation is still under way.