A jealous prostitute killed her lover in a "deliberate and brutal" knife attack after he admitted cheating on her with other escorts, a court has heard.

Dionne Liza Neale, 39, is accused of murdering 38-year-old advertising executive Reece John Shadbolt in his Parnell apartment on Waitangi Day two years ago.

In the High Court at Auckland yesterday, prosecutor Kevin Glubb said Neale stabbed Mr Shadbolt nine times with a carving knife in an assault that began in the shower.

The pair met in 2004 at the Mustangs Gentleman's Club on the North Shore, where Neale worked as an escort.

They eventually lived together, but broke up when a business they had invested in collapsed, leaving both of them destitute.

In late 2006, they started seeing each other again.

Neale helped Mr Shadbolt move into his new Parnell home in February 2007 and two days later joined him there for dinner.

But the Crown claims Neale went to dinner to ply Mr Shadbolt with alcohol, then confront him about visits to inner-city brothels.

Mr Shadbolt - the man behind the Carlos Spencer Toffee Pop advertisements - confessed to his "on again, off again" girlfriend of two years that he had been to massage parlours.

Despite the admission, the couple slept together before Neale left.

On the way out, she is alleged to have scratched his car with the words "cheater" and a badly spelt attempt at "whore addict".

The next day, Mr Shadbolt sent her a text message asking her "Why did you go?" and took a photograph of the damage.

Three days later, Neale returned uninvited to the Parnell apartment on the morning of Waitangi Day, before Mr Shadbolt left to play golf.

The couple shared a cup of tea, then Mr Shadbolt went to the bathroom.

Mr Glubb said Neale grabbed a large knife and plunged it through her boyfriend's chest while he was in the shower.

The knife penetrated Mr Shadbolt's heart and lungs.

The wounded man staggered from the bathroom and down the hallway - where blood was splattered on the walls in signs of a struggle - before collapsing in the lounge.

Mr Shadbolt was stabbed a further eight times: in the back, throat, shoulder, arms and torso.

"He was left there lying in a large pool of his own blood," Mr Glubb told the court.

Neighbours heard the attack and knocked on the door, but did not investigate further when there was no answer.

Mr Shadbolt's body was not found for 12 hours, when lawyer Marie Dyhrberg rang 111 after receiving information from a friend of Neale that a man had received a life-threatening knife injury.

Called as a witness yesterday, Ms Dyhrberg said she told the emergency operator that police would have to break into the Parnell address, as the man was unlikely to be responsive.

Mr Glubb said Neale sought medical treatment for a knife wound to her hand, and later had surgery to repair a tendon.

Forensic scientists found a mixture of Neale's and Mr Shadbolt's blood in the Parnell apartment and in linen and clothing found at Neale's home in Beach Haven.

Traces of the mixed blood were also found in her car.

The trial is expected to last for four weeks.