Brendan Leigh Russell went beyond breaching a duty of care towards his clients and displayed gross negligence on multiple levels, Dr Ron Bezic said.

The cosmetic surgeon gave evidence in the NSW District Court on Thursday about a woman who allegedly contracted septicemia and died after Russell implanted a plastic snowflake in her hand.

Russell has pleaded not guilty to the charges of her manslaughter and to female genital mutilation related to another woman he operated on in 2015 and 2017.

The 40-year-old also denies intentionally causing grievous bodily harm to a woman in the back of his workplace Transition in Erina Fair Shopping Centre in November 2016.

The identities of each woman have been suppressed by the court

Earlier the court was told Russell, known by the moniker Bslice Dot Com, had performed a number of procedures on the late woman including a heart implantation on her finger, and the stretching of her inner ear.

But one of her friends, who is a body piercer, said other procedures such as a nipple reconstruction and a sub-dermal implant were "not her idea".

The snowflake was first cut into her hand on March 20, 2017, and she returned on April 10.

"She had obvious signs of acute infection, red swollen hand, a large amount of pus," Dr Bezic said.

A witness to the event says Russell told the woman "it's not infected, just irritated".

While the woman reportedly spoke of "serious pain", graphic videos recorded Russell moving the implant around underneath her bloodied skin, and not washing the wound.

This manipulation of the skin tissue encouraged the spread of any present bacterial bugs into her bloodstream, Dr Bezic said.

"Implant surgery ... in the setting this occurred in, eventually someone will develop the complications she did and will die from them."

A friend of the deceased woman told the court she had become obsessed and sexually attracted to Russell and had slept with him at least once.

The industry peer reported Russell's "dangerous" procedures to health authorities and police.

"To prevent anyone from being seriously harmed," he said.

He also created an anonymous social media page to Russell's "reckless disregard for the safety of his clients".

"Brendan had a cult-like following, and those opposed (to him) were I guess targeted."

He regularly shared these worries with his friend but she was very sure about Russell's skills and "trusted him entirely", he said.

But this made her cut all ties with him one year before she died, he said.

Defence lawyer Michal Mantaj said his client's industry competitor had been angry at perceived online slander from him, and made up much of his evidence.

But the friend denied this.

Senior health officer Kerry Spratt told the court she visited Russell at work in October 2016 following a number of complaints.

"He said many people come in to have him fix procedures that doctors have botched ... and that he travelled the world training people about how to do body modifications," she said.

He was given printed material from NSW Health on infection control but said he had seen it all before and had undertaken a relevant course.

The judge-alone trial continues.

Australian Associated Press