Murderer Derek Barrett gets more prison time after mystery USB revealed ‘despicable’ sex assaults

A judge has lashed murderer Derek Barrett after new evidence of sadistic rapes he inflicted on his step-niece before killing her came to light in a baffling way.

Killer Derek Barrett would have been sentenced to life in prison if footage of the depraved sexual assaults he committed before murdering student Mengmei Leng had been discovered earlier, a judge has said.

Barrett, 32, was previously sentenced to 46 years in prison for stabbing Ms Leng, his step-niece, multiple times before dumping her body in the ocean on the NSW Central Coast in April 2016.

But the sentence, which expires in 2062, did not reflect the multiple sexual assaults he inflicted on the 25-year-old Chinese student before taking her life.

Barrett recorded his sadistic sexual crimes from multiple camera angles, capturing 60 minutes of tape in which his brutality and contempt for Ms Leng was on full display, as was her pain, distress and fear.

Police did not discover the footage in their initial investigation, and Barrett would have gone unpunished for the acts were it not for a freak event that baffles detectives to this day.

Mengmei Leng, a Chinese national, was 25 years old and studying in Australia when she was killed.

The footage surfaced when, for reasons no-one can explain, an elderly woman with dementia in Strathfield somehow obtained a USB containing nine videos and 13 photographs of Barrett’s sick scene.

In November 2019, the woman’s daughter visited, noticed her mother was holding the memory stick, plugged it into a computer, and called police.

The footage, Supreme Court Justice Harriet Wilson said on Thursday, lays bare how Barrett took pleasure in “hurting, humiliating and degrading” Ms Leng before killing her.

“The offender manipulated Ms Leng’s body as if she was a worthless, inanimate object,” she said.

At one point, the judge said, Barrett noticed he had bound Ms Leng’s hands so tightly they were swollen and turning purple.

He stopped to cut off the duct tape with a large hunting knife, re-tied her hands, and said: “Now, where were we?”

He then continued to rape and assault her.

“I would go so far as to say that had the court known the full extent of abuse and violation of Ms Leng a life sentence would have been imposed,” Justice Wilson said.

“That sentence cannot now be imposed.”

How a USB containing footage of Derek Barrett’s depraved crimes landed in the hands of an elderly woman in Strathfield remains a mystery. Picture: John Grainger

She sentenced Barrett to an additional 20 years in prison, but it will be served concurrently with his murder sentence, meaning his 46 year overall sentence remains unchanged.

The practical effect of the ruling makes Barrett eligible for parole in October 2052, rather than October 2050.

Barrett, a large, balding man with glasses dressed in a prison green tracksuit, did not react as the sentence was handed down.

He raised his eyebrows several times as Justice Wilson spoke, including a reference to “sadistic sexual killers” and as she dismissed as false his claims to have been on drugs and have no memory of the assaults.

Barrett’s letter to his victim’s mother was “formulaic” and did not indicate real remorse, Justice Wilson said. Picture: Supplied.

As the judge rejected an apology letter he wrote to Ms Leng’s mother as “formulaic” and disingenuous, he shook his head as if frustrated.

“To be accepted as such, real remorse requires more than the utterance of a few well-worn words,” the judge said.

“It requires a genuine acknowledgment of wrongdoing, and a deeply felt regret for it. It is hard to see how the offender could truly regret conduct he claims not to remember – I am satisfied falsely - and blames upon drugs.”

Justice Wilson said the evidence of forensic psychiatrist Richard Furst was that Barrett was a sexual sadist whose risk of killing again was between 10 and 100 times greater than the average person.

In prison Barrett would likely “go through the motions” of participating in a sex offender program but it would have little effect on his risk of re-offending, Dr Furst testified.

Justice Wilson said there was almost nothing for Barrett to rely on when it came to factors that might mitigate his wrongdoing, bar his lack of priors and the sentencing principle of totality.

The law required her to view the sex crimes as part of Barrett’s overall offending against Ms Leng, beginning with her detainment and ending with her murder, both of which he had already been sentenced for, she said.

This worked heavily in Barrett’s favour, she said, noting that the two separate sentences did not represent the whole of what he did.

Ms Leng’s mother Mei Zhang was unable to attend the sentencing, but told the court the awful revelation of what her daughter went through made the loss harder to bear. Picture: John Grainger

How the woman in Strathfield came into possession of the USB four years after Ms Leng’s murder remains unknown.

The woman had no discernible connection to Barrett, did not leave her house other than to venture into her front yard, and lived six kilometres from his former home in Campsie.

Police believe the mystery may never be solved.

But the “additional blow” of what lay on that USB exacerbated the horror and grief felt by Ms Leng’s mother, Mei Zhang, about her daughter’s fate.

Ms Zhang is in China and could not travel to Australia for the sentencing proceedings due to the COVID-19 border closures, Justice Wilson said.

But in a translated statement, Ms Zhang said her unimaginable loss was now even harder to bear.

“As she said to the court, how could any mother accept such news?” Justice Wilson said.

“The simple answer is that no mother, no parent, no decent person, ever could.”

Originally published as Murderer Derek Barrett gets more prison time after mystery USB revealed ‘despicable’ sex assaults