Dressed in a suit and tie, Brian Crickitt sat in the dock just a few metres away from his step daughter as the court was told of the “awful sadness” she had endured.

Tracey Wiggins told the court of having to grapple with the knowledge her mother “died alone, discarded and rejected.”

She added: “I have been shattered by the betrayal and the cold hearted actions of my step dad.”

Crickitt faced a sentence hearing in the Supreme Court this morning for murdering his wife Christine Crickitt with a fatal dose of insulin at their home in Woodbine, in Sydney's south-west, on New Year’s Eve in 2009.

The 63-year-old’s trial heard in the days before he killed her, he Googled “intentional insulin overdose” and wrote a prescription for the drug in another patient’s name.

Brian Crickitt (L) is accused of murdering his wife with a fatal dose of insulin. Pictured with second wife, Julie. (AAP)

He injected her, then spent the night with his mistress.

The next date he denied that woman’s existence and told police it was his wife “or nobody as far as I’m concerned.”

The local GP was accused of murdering Mrs Crickitt because of his increasing dislike for her, his desire to be with his mistress, and to get his hands on more than half a million dollars in life insurance.

Lats year Justice Clifton Hoeben found "not only am I satisfied it would have provided an adequate motive, I have concluded that it was in fact the primary motive.”

He was taken into custody that day.

Today the crown argued it was a pre meditated crime that deserved a very severe penalty, but they were not asking for the maximum of life behind bars.

The defence asked for a sentence that would give him hope of release.