An investigator hired by the Salvos told the Royal Commission into Institutional Responses to Child Sexual Abuse on Monday that Lieutenant-Colonel Colin Haggar allegedly assaulted the girl three times, not once as the officer had claimed, and that there was no direct documentary evidence that the police confession ever took place.

The revelations came from a former detective, John Greville, who joined the Salvation Army's professional standards office in January, and was charged with investigating Colonel Haggar, who had admitted to sexually abusing an eight-year-old girl on one occasion in the state's central west in 1989.

Mr Greville told the commission on Monday that, upon taking up the job, he discovered that files in relation to Colonel Haggar were in chaos, and that it appeared the matter had never been investigated.

"I found no evidence of any questions being asked of officer Haggar, or the victim, or the victim's family," Mr Greville said. "To me that would be the basic level of investigation that would be required."

When Mr Greville interviewed the woman who had been abused when she was eight, something the Salvation Army had never done, she said there had in fact been three instances of abuse, not one.

"I am quite confident that what he admitted to at the time is far different to what is alleged to have occurred," Mr Greville said.

"You're looking at three instances, each progressively worse than the previous one."

The investigator also cast doubt on Colonel Haggar's claim that, not long after the abuse, he and the now Salvation Army Commissioner, James Condon, went to police and confessed what had happened but were told nothing could be done.

"There was no direct statement or comment [on file] that officer Haggar, accompanied by the then Captain Condon, reported the matter," Mr Greville said. "There was reference in other documents that that's what had occurred, but there was no direct comment."

The commission also heard that a 60-year-old intellectually disabled woman claimed she, too, was abused by Colonel Haggar while taking part in an Salvation Army-run support program.

The woman never made a police statement about the alleged incident and Colonel Haggar denies it took place.

Earlier, Colonel Haggar's wife, Kerry, tearfully apologised for sending an accusatory Facebook message to the fellow officer who reported his abuse to the authorities. But Mrs Haggar, who is also a Salvation Army lieutenant-colonel, denied she was trying to intimidate the woman just weeks before she was due to give evidence at the commission's public hearings. "I'm incredibly sorry and I'd like to reiterate publicly to Michelle my apologies for sending that," Mrs Haggar said of the whistleblower, Captain Michelle White. "It was a very personal reaction out of my own distress."

Colin Haggar has been forcibly retired from the Salvation Army. Kerry Haggar is on "indefinite leave" and has been stood down from her previous role. Both have been permitted to retain their formal titles.