But she disagreed on whether his narcissism – shown in his lack of empathy and eagerness to dominate relationships – amounted to a disorder, and further concluded that he had exhibited traits of psychopathy, such as superficial charm and limited remorse or guilt for his behaviour.

She said the “disinhibiting effects of cocaine and alcohol exaggerated [Jutting’s] propensity to act out fantasies and impaired control, which subsequently led to the killings of these two victims”.

But this impairment, she said, did not amount to being “substantial” – a threshold required for the defence to argue diminished responsibility.

Defence counsel Tim Owen QC asked in response: “What, Dr Chow, is your definition of substantial?”

“Substantial, from my view, is more than trivial, less than total impairment,” the psychiatrist replied. “In Mr Jutting’s case, although his control was impaired by disinhibiting effects of alcohol and cocaine, all evidence ... suggests he did understand the nature and consequences of the killings.

“Whether it is trivial is a matter for the jury to decide,” she added.

But Owen questioned how his client could have controlled his intake when his substance use showed dependence, tolerance and craving.

Chow said even a severe disorder would allow the ability to control one’s intake.

“Dr Chow, with all my respect, your evidence is absurd, contradictory. Have you ever given evidence for the defence?” Owen asked. Chow said no.

Meanwhile, another psychiatrist for the prosecution, Dr Oliver Chan, testified that it would be difficult for Jutting to resist the craving. “But it would not deprive him of the ability to resist it,” he said.

Chan was confident that Jutting’s ability to control his function was not substantially impaired.

A line in his report read: “He should, despite the craving and dependence, be capable” of stopping cravings.

But Owen pointed out that the exact line also appeared in Chow’s report. “Is the jury to conclude that it’s a coincidence?” he asked. Chan replied the reports were prepared separately.

He, unlike the three other experts, did not find Jutting suffered from sexual sadism disorder as he found that the Briton’s sexual interest had yet to affect his functioning.

“You are,” Owen said, “an incredibly arrogant man .... Graduated and qualified in 2013, first case of sexual homicide. You think they are all wrong.

“Do you regard a man who spends almost 24 hours a day reading hardcore pornography as someone operating normally?” he asked. Chan replied no.

It emerged from Chan’s evidence that Jutting picked small Asian girls because they would be easier to handle, and that he had also said he loved Sumarti just before he slit her throat.

The court heard that Jutting’s cocaine use increased to up to 20 grams a day the month before the killings as he became acquainted with a drug dealer who could provide him with the drug whenever he wanted it.

He was also consuming two to three cans of Red Bull and a bottle of spirits every day, which later became two bottles closer to the killings.

“From the evidence I had, I don’t think Mr Jutting had tried to control [himself],” Chow said.

Reading from her report, prosecutor John Reading SC further revealed that Jutting continued to masturbate daily and still had fantasies of rape and kidnap even while he was remanded at Siu Lam Psychiatric Centre after his arrest.

She was told that he respected sex workers and engaged in rough sex only with those who consented – until he met the first victim, Sumarti, whom he treated as an instrument.

The court also heard for the first time that he conducted an experiment on Sumarti to see if she accepted death by tying a towel around her neck.

When she did not resist, he killed the Indonesian as he felt in control and that he was no longer excited.

Jutting had no criminal record. But he did admit to the psychiatrist that he stole books from a Cambridge bookstore 15 to 20 times.

The trial continues before deputy High Court judge Mr Justice Michael Stuart-Moore.