The RCMP have been under fire in B.C. in recent years after incidents involving the use of stun guns, deaths in custody, and drinking and driving. (CBC)

RCMP in Metro Vancouver acknowledge staff morale has suffered following the revelation a senior investigator on the notorious Surrey Six homicide investigation is himself under investigation.

The officer, a member of the regional homicide investigation team, was assigned to desk duty after an allegation came to light in December that he was carrying on an inappropriate relationship with a potential witness in the case.

Chief Supt. Janis Armstrong said the RCMP are taking the allegation seriously, and the professional standards unit is conducting an internal investigation.

'Should the allegations ring true, then yes, he should have known better.'— Chief Supt. Janis Armstrong

"I would characterize him as a seasoned investigator, and should the allegations ring true, then yes, he should have known better," Armstrong said.

RCMP have denied media reports the unidentified officer was romantically involved with a girlfriend of one of the accused but have yet to reveal specific details about the allegation.

Allegations undermine good work

On Wednesday morning, RCMP officers arriving at the headquarters of the homicide investigation team in Surrey found reporters at their front door.

"What was he thinking?" one officer once arriving at the building asked a CBC reporter.

Another officer expressed frustration at having to defend the force when so much good work has been done to investigate the gang-style slaying of six people in a Surrey highrise in October 2007.

One man, Dennis Karbovanec, 28, has already pleaded guilty to three counts of second-degree murder in the case and was sentenced to life in prison. Four other men are awaiting trial on charges of first-degree murder and conspiracy to commit murder.

Sgt. Peter Thiessen acknowledged that officers are angry and embarrassed about the recent developments.

"If the allegations are substantiated, then yes, it certainly is embarrassing," Thiessen said. "It's difficult to come forward and address these allegations."

But any information the witness may have provided has not been used in any legal proceeding so it would not compromise the outcome of the Surrey Six case, the RCMP said in statement on Tuesday.

The RCMP have been under fire in B.C. in recent years after incidents related to the use of stun guns, deaths in RCMP custody, and drinking and driving by officers.