In his opening address to Newcastle Supreme Court on Monday, Crown Prosecutor Lee Carr said Mr Dasilva's behaviour became increasingly erratic after his break up with Wyong High School maths teacher, Amanda Carter, 46.

The real estate agent is alleged to have entered Ms Carter's Woongarrah home in May 2010 and delivered a number of blows to her head using a blunt object, while she lay sleeping in her bed.

The court heard she was discovered by her daughter the next day, with no signs of forced entry to the house.

Mr Dasilva has pleaded not guilty to murder and claims he fell asleep watching television on the night in question.

A paramedic who attended the scene testified that Ms Carter's injuries were so severe, he was unable to identify where her nose should have been.

Mr Carr said it appeared Mr Dasilva tried to burn the house down after the attack, after police found a frypan half full of olive oil on the stove, next to a hot plate that was "radiating significant heat".

Mr Carr told the jury the victim had become increasingly fearful for her safety after her relationship began to "sour" with Mr Dasilva in 2009.

The jury would hear evidence he sent letters to a number of media outlets, falsely accusing Ms Carter of having an affair with a student.

After she sent him a text message saying "no communication is the only option", he is alleged to have sent her 32 emails in less than a month.

In another incident, Mr Dasilva is alleged to have called Ms Carter to say he had taken 40 pills and "would not be seeing her again."

Mr Dasilva would also turn up at her home uninvited, prompting Ms Carter to attempt to take an apprehended violence order out against him in the weeks before her death, the court heard.

In an email to a friend Ms Carter wrote: "Richard seems to have gone past the non-accepting stage and is entering the angry stage."

Defence counsel Alissa Moen asked the jury to keep an open mind.

The trial is expected to run for at least six weeks.

Newcastle Herald