Detective Inspector Peter Fox at home late last month. Photo: Peter Stoop

A senior detective who blew the whistle on an alleged police cover-up of sex abuse in the Catholic Church said he had received threatening messages on police letterhead since speaking out on an issue that he acknowledged would end his career in the force.

But after Prime Minister Julia Gillard announced a sweeping royal commission into child sex abuse on Monday, Detective Inspector Peter Fox said he felt vindicated and satisfied that the thousands of voices of abuse victims would finally be heard.

The senior investigator’s explosive allegations on Lateline last week – that the Catholic Church had covered up crimes of paedophile priests and silenced police investigations in the Newcastle-Hunter area of New South Wales – helped to trigger the royal commission, which will probe organisations ranging from church and state authorities to the Boy Scouts and sports groups.

Detective Inspector Fox said the royal commission was a “wonderful result”. He said the push for the inquiry had affected him and his family, including his wife, who suffered a nervous break-down after receiving threatening letters.

He had also received an anonymous threatening letter with police letterhead from a “disgruntled officer” after speaking out about the church and another controversial issue in the past year.

A smear campaign had also been launched against him, with rumours circulating in the police force that he was mentally unstable, Detective Inspector Fox said.

“I don’t want to go into it too deeply, but this is the end of my policing career,” Detective Inspector Fox told Lateline on Monday night.

“I realised that from the moment that I decided to speak out last week. As much as it’s denied, the culture within the police force would never allow someone like me to move back into it.

“I think the Wood Royal Commission [into police corruption in NSW] uncovered it years ago and I’m sorry to say that very little has changed. You know, ostracisation and things of that nature continue to go on within the police force.

“Don’t get me wrong, I’m not bitter with the police force. They’re a minority, those individuals, but they exist everywhere, whether it’s the police force or wherever else in society they may be. We will probably unfortunately never change that.”

Detective Inspector Fox said the royal commission should examine aspects of the Catholic Church such as confession, in which priests had been known to confess to other priests their abuse of children.

“We need to get laws to stop that happening and to compel those priests that are hearing those confessions to say, ‘Listen; God doesn’t want this man to commit more crimes. He wants me to come and tell the police to stop him’,” Detective Inspector Fox said.

He also hit out at Sydney Archbishop Cardinal George Pell’s claims that the royal commission was brought about by ongoing and at times one-sided media coverage.

“It certainly has been one-sided, because it seems to be the Church that has been continually screaming out the message that ‘We don’t need a royal commission, there’s nothing going on here, move along’,” Detective Inspector Fox said.

“We’ve had enough from that one side, Mr Pell. Now we’re going to start listening to the victims and start listening to their families and we’re going to start doing something about the problem.”

Detective Inspector Fox joined Twitter last week in his campaign for a royal commission.

On Monday night he tweeted: “I will sleep with a smile.”