Alberta Serious Incident Response Team (ASIRT) investigators, who look into allegations of possible police wrongdoing, are themselves being investigated by a senior Edmonton police officer, CBC News has learned.

The investigation stems from an incident last year involving RCMP Cpl. Kelly Gulaga.

Gulaga was investigated by ASIRT, and last September was charged with five counts of assault, one count of forcible confinement and three weapons offences.

An Alberta court was told the incident involving Gulaga was a domestic situation.

Gulaga was suspended with pay, then resigned a month later.

The charges against Gulaga — except for the weapons offences — were withdrawn earlier this month.

On Monday, a lawyer in St. Albert, Alta., appeared on behalf of Gulaga to enter not guilty pleas in the weapons offences.

Court documents show the 41-year-old is accused of possessing a prohibited weapon — a butterfly knife. Gulaga has also been charged with taking his service pistol home and not safely securing it there.

The police who investigated the Gulaga case are now being investigated themselves.

Edmonton Police confirmed to CBC News they are investigating three officers who were seconded to ASIRT.

An Edmonton senior inspector has been appointed to look into criminal and code-of-conduct allegations and is probing why the assault charges were laid and then dropped.

"We are here to ensure that the public has an increased sense of confidence in policing in the province of Alberta," Cliff Purvis, ASIRT's executive director, told CBC News.

"I look forward to the investigation being thorough, objective. Just like we would produce if we were investigating another police agency."

Purvis said ASIRT members are co-operating.

"ASIRT doesn't have a black eye yet. It has to be investigated thoroughly for the public to continue to have confidence in ASIRT," Purvis said. "So we're co-operating with the investigation and I look forward to its outcome."

A trial date on the weapons charges will be set next Monday.

With files from the CBC's Janice Johnston