A doctor who stabbed a 16-year-old girl to death because she threatened to expose him for allegedly sexually assaulting her has been found guilty of murder.

Dr Venod Skantha, 32, killed Amber-Rose Rush after sneaking into her home in Dunedin in New Zealand on the night of February 2 last year.

The Crown alleged Skantha killed Ms Rush to silence her after she posted a series of messages between the pair on Instagram, which would have ruined his medical career.

Ms Rush met Skantha through a mutual friend at a party in the doctor's home in mid-2017. Their mutual friend, a teenage boy, became the prosecution's key witness.

The pair spent a lot of time together over the coming months, with the teen's friends describing Skantha's interest in her as 'creepy'.

Amber-Rose Rush (pictured) was found in a pool of her own blood in her bed at her family's home in Dunedin, New Zealand in February last year

But in January 2018, just a month before her murder, the pair had a falling out.

Ms Rush told her friends she woke up in Skantha's house to find him molesting her.

'She told me she'd woken up with her bra off and Vinny's hand down her pants,' the witness told the court, according to the New Zealand Herald.

'I don't believe she was lying to me.'

During the trial, the court heard Skantha offered money to Ms Rush to have sex with him, which the defence agreed had happened.

'Initially it was $2000 and then it went up to $20,000 when she denied him,' her friend told the court, Radio New Zealand reported.

'She told me she ended up slapping him in the face and getting herself picked up and leaving as soon as possible.'

Dunedin doctor Venod Skantha was found guilty of murdering Amber-Rose Rush, after sneaking into her bedroom and stabbing her several times

The two parted ways after the incident, until Skantha messaged the teen on February 2 after an online purchase was made using his credit card.

Ms Rush denied making the purchase, before Skantha told her to stop spreading rumours about his behaviour.

She responded with a message which read: 'Stuff doesn't mean s**t when you did that to me, wasn't talking s**t hun you should own up to what you did, fkn perv.

'You're lucky I don't go into the hospital and tell them how you turn up to work drunk, and supply minors with alcohol, touch them up without consent, grow up vinny you're 30 for f**k sakes.'

Ms Rush then posted screenshots of their messages to her Instagram account.

The pair's mutual friend - the prosecution's star witness - then alerted Skantha to the posts.

Mr Rush and Skantha's texting argument then started again, with the teen telling the doctor she was going to tell his bosses as well as police about his actions.

Her last message to Skantha read: 'You know what you were doing when you did it. For that you deserve everything you're gonna get'.

Just 30 minutes after sending that message, Ms Rush was murdered.

Prosecutors said Skantha was driven to Ms Rush's home by the teenage witness, whose name was suppressed.

Skantha then entered the home using a spare key, and stabbed Ms Rush in her bed with a knife he brought with him from home.

She suffered multiple stab wounds in the back of her neck.

'The person who did this, was really, really angry,' Prosecutor Robin Bates told the High Court of Dunedin on Tuesday.

Ms Rush met Skantha through a mutual friend at a party in the doctor's home in mid-2017, before their friendship went south when she claimed the doctor put his hands down her pants while she was alseep

Bates said the doctor knew to stab Ms Rush's carotid artery and windpipe, and described it as 'not some random clumsy attempt,' but an attack to silence the teen.

He told the court Skantha was 'hellbent on getting rid of the contents of [Amber-Rose's] phone'.

Skantha stood to lose his job after being given his final warning at Dunedin Hospital, Stuff reported.

But Skantha's lawyers argued the case's star witness, who idolised Skantha, was involved in Ms Rush's death in a desperate bid to save his career for him.

The judge reminded the jury they needed to believe beyond reasonable doubt that Skantha murdered the teen, and that he threatened to kill her.

But he said the jury didn't have to acquit Skantha if they found the teenage witness, whose remain remains suppressed, was an accomplice.

The judge urged the jury to evaluate the credibility and honesty of the witness.

But defence counsel Jonathan Eaton QC blamed the Crown's key witness.

'He is the person who is at the heart of this case. I suggest he would do anything to protect Venod Skantha,' Eaton said in front of a packed court room.

Eaton argued that Skantha should be acquitted due to the evidence of the witness, who admitted to being a 'compulsive liar' in his police interviews.

Skantha was remanded in custody and will be sentenced on March 6.