The special constable murdered on the orders of her cheating husband abused her official position while helping him to run an escort agency, according to secret police files.

The documents reveal that Nisha Patel-Nasri, who was stabbed to death at her home, allegedly drove call girls to work and used her police warrant card to threaten clients over unpaid bills.

The claims about her murky business affairs were not made public at the murder trial of her husband, Fadi Nasri, and will raise questions about the vetting procedures of the Metropolitan police.

Nasri faces life in prison after being convicted last week at the Old Bailey of organising a hit man to kill his wife, 29.

The court heard that Nasri, 34, plotted to collect the couple’s £367,000 life insurance and use it to finance a new life with a Lithuanian prostitute with whom he had fallen in love.

During the trial Nasri admitted running an escort agency called Seventh Heaven, which employed up to five call girls offering sex to clients at £120 an hour. Nasri told the court that he had decided to close down the business, which was run from the couple’s home in Wembley, northwest London, after his wife said she was unhappy with it.

However, confidential police investigation documents suggest that the special constable, who joined the Met in December 2002, was closely involved in the agency’s affairs.

A police officer told the murder investigation team that he had reported Patel-Nasri to the Met’s anti-corruption unit after he became concerned about her activities. But he said no action was ever taken.

Patel-Nasri, a hairdresser, was murdered in 2006 after her husband gave his house keys to a knifeman who had been hired for £15,000. She was stabbed as she attempted to flee her killer and bled to death on the pavement outside her home.

At her funeral, Patel-Nasri’s coffin was draped with the Met police flag and given a guard of honour by 100 officers. Sir Ian Blair, the force commissioner, said her death was a huge loss to the police service.

However, evidence from David Eden, a Hertfordshire police sergeant, and from a call girl who worked at the escort agency paints a more complex and disturbing picture of Patel-Nasri’s life.

Eden said in a police statement that he met Patel-Nasri in 2003, shortly after she became a special constable.

A client of Seventh Heaven was disputing a £700 bill, and Patel-Nasri, her husband and other men had gone to his home in Elstree, Hertfordshire, to collect the outstanding money.

The client, known as J, alleged that they had tried to force their way into his house, with Patel-Nasri showing her warrant card and claiming to be on official police business. The client also claimed that Patel-Nasri had previously supplied him with cocaine at £50 a gram.

When Eden arrived in response to a 999 call made by the client, Patel-Nasri told him she had used her warrant card only as identification.

“She was very aggressive,” Eden recalled in a statement after her death. “She told me that I had no idea who I was f****** with — that I was a county force sergeant and her powerful friends at Scotland Yard could have me out of a job. She advised that my officers and I withdraw from the scene and allow them to get on with their business if I knew what was good for me.”

In his statement Eden said that Patel-Nasri claimed to own the escort agency. He subsequently contacted the Met’s professional standards department and sent a formal complaint to Wembley police station, where Patel-Nasri worked.

Eden approached the Met again with this information after the murder but was told that copies of his earlier report could not be released. He later discovered that the hard disk of his Hertfordshire police computer, where he had stored a copy, had been wiped.

Eden’s evidence about Patel-Nasri is supported by the testimony of a woman called Maria who worked for Seventh Heaven. In a witness statement last year she described how Patel-Nasri helped — and later threatened — her in her work as a prostitute.

“I knew that Nisha was a policewoman but I couldn’t quite believe it sometimes,” Maria said. “She drove me to a job in east London once in her own car, which was a sports car, and she was speeding.”

Maria claimed that Nasri once assaulted her over some unpaid money. She said: “[Nisha] said to me that I shouldn’t go to the police or press charges about the earlier incident because if I did she would ring my boyfriend and tell him what I was doing.”

In a police statement, Maria added: “Nisha used to ring me up all the time and tell me that I had to work, otherwise I was losing her money . . . I was aware that Nisha had apparently used her police badge to recover debts and I was aware of [Nasri] being violent towards clients.”

Last night a Metropolitan police spokesman said that Patel-Nasri was disciplined for using her warrant card inappropriately. She was given a formal verbal warning.

He added: “When Nisha applied to be a special constable in 2002, the correct procedures that were in place at the time were carried out, according to the information she supplied on the form.”

About 12,000 part-time special constables work for the police across England and Wales. The Met has 2,000 specials and recently announced plans to expand the force to 6,000 officers in time for the Olympics in 2012. They wear the normal police uniform and carry a warrant card that gives them the same powers of arrest and search as full-time officers.

They also have access to the police national computer, which contains sensitive personal information including the records of everyone who has been arrested or convicted of an offence.

The security service MI5 has been forced to review its own vetting procedures after it discovered that one of its intelligence officers was married to a call girl who was involved in an alleged “Nazi-style” sadomasochistic orgy with Max Mosley, the boss of Formula One racing.

This weekend one of Patel-Nasri’s two brothers said he was not surprised by the claims. “They painted Nisha like she was an angel, but in reality she was always up to mischief and no good,” said Pilesh Patel.

“There was a nice side of her. She was generous with her money. But the other side of her was that she was very selfish. Once she got into the position she had as a special constable, I could see her abusing that position for her own gain.”

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