This trail of evidence of fraud, lying and cover-up now roils around the federal Labor MP Craig Thomson. It has also engulfed the NSW Police Force, which implausibly refused to act until a victim had filed a complaint.

''Utter garbage,'' said the former detective. ''Police do not need to have a complaint from a victim in order to investigate a crime.''

Even more damning, the victim in this case, the Health Services Union, clearly had no interest in bringing a complaint because the moment this became a criminal matter it would become a time bomb ticking beneath the Gillard government.

It began to tick on Tuesday afternoon when police issued a statement saying that material submitted by the federal shadow attorney-general, Senator George Brandis, would be assessed to see whether a crime had been committed. If the police cannot find a crime here, then it is the police who will need to be assessed.

As for the reluctant Health Services Union, it would have had its own case to answer, had it not announced yesterday it would be co-operating with police. Section 316 (1) of the NSW Crimes Act makes it an offence to conceal knowledge of a serious indictable offence: ''If a person has committed a serious indictable offence and another person who knows or believes that the offence has been committed … fails without reasonable excuse to bring that information to the [police] … that other person is liable to imprisonment for two years.''

''It is difficult to understand why it took [the police] so long to act,'' said the former detective. ''I believe a union member went into a central coast police station attempting to make a complaint but was turned away … We are not talking about a complicated case. Given resources, this brief would represent two to three weeks' work before somebody could be charged.''

Tick, tick, tick.

What kept a lid on this for the past two years was a defamation claim Thomson lodged against this newspaper. When the time finally came to attend court, he withdrew the action. Labor then paid his unhealthy legal bill. It was all done privately, but the public time bomb is now ticking for multiple reasons.

In 2003, 2005 and 2006, Thomson's corporate credit card was used to pay escort services in Melbourne and Sydney while he was national secretary of the HSU. He says his signature on receipts to escort agencies were forged.

A handwriting expert, Paul Westwood, formerly of the Australian Federal Police, compared the signature on Thomson's driver's licence with the signature on a credit card voucher and concluded they were probably made by the same person.

Thomson tried to reverse three payments made to an escort agency on his corporate credit card by using his personal credit cards.

Mobile phone records show that Thomson's phone was used to call escort agencies.

In 2008, the national secretary of the HSU, Kathy Jackson, now the union's executive president, wrote to the law firm Slater & Gordon claiming Thomson's credit card had been used for a number of transactions that were for private use or for his election campaign. The amounts totalled more than $70,000.

In Parliament yesterday, Thomson was asked to account for $39,454 in electoral expenses, incurred via his corporate credit card, that had not been declared to the Australian Electoral Commission.

In an interview on 2UE, Thomson, reiterating that the signature on receipts to escort agencies were not his own, said: ''The union reached a settlement with another gentleman who paid back $15,000 in relation to use of credit cards at an escort agency.''

But it has emerged that the $15,000 payment he referred to had nothing to do with escort services.

Twice yesterday, the government was able to defeat opposition motions to compel Thomson to explain his conduct, then for the Prime Minister to explain her confidence in Thomson, with the automatic support of the Greens MP, Adam Bandt, plus the rural independents Tony Windsor and Robert Oakeshott, who, like Thomson, are accelerating the end of their parliamentary careers.

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