A man who feigned symptoms of mental illness for more than 18 months after murdering a girl and stabbing her friend was "not very bright", according to a forensic psychiatrist.
Kristian Kovaleff, 21, has pleaded guilty to murder and wounding with intent to cause grievous bodily harm.
The two 17-year-old girls, one who survived the December 2020 attack inside a Parramatta Meriton hotel room while celebrating the other's upcoming 18th birthday, cannot be identified.
About two hours after stabbing the girls, Kovaleff eventually called for an ambulance, but hung up.
He told the operator someone else attacked the "one person dead and another bleeding out inside room 111" when they called back.
It was among many lies Kovaleff would tell, becoming so numerous he struggled to keep track of them while feigning symptoms of mental illness for more than 18 months.
Forensic psychiatrist Richard Furst told the NSW Supreme Court on Wednesday Kovaleff had dropped the act by November 2022.
"It was a consensus by that stage that the symptoms he was reporting of psychosis ... were not real," Dr Furst said.
Asked whether a psychiatric illness or personality disorder could help explain the crime, Dr Furst said he could not make a specific diagnosis.
"I don't think he's very bright, I think I can say that reliably," Dr Furst said.
"There's a caveat on everything because he's dishonest."
Crown prosecutor Monica Millward submitted Kovaleff's offending stemmed from possessiveness.
"A possessiveness ... often seen in serious domestic violence offending," she said.
Kovaleff wanted to kill one of the girls so "no one would be able to get with her after", as he told the court.
He began planning a month before he murdered her friend and stabbed her, leaving her vomiting blood and spending eight days in hospital.
The day before the murder he bought a new phone and searched for "tools that can be used as weapons", purchasing duct tape, rope and a handsaw the next day.
While they were not used in the attack, Kovaleff's public defender Tony Evers acknowledged he brought the duct tape to the hotel "in part to silence any screams".
Kovaleff already owned, and frequently carried, the knife, but denied having it when asked by one girl.
He hid it under a couch cushion before the attack and it was later found in the hotel room's dishwasher.
Mr Evers said Kovaleff was remorseful soon after killing one girl and stabbing the other.
"He took steps ... to try and treat (the wounded girl)," Mr Evers said.
The girl asked him to call an ambulance twice, but he refused, according to the agreed facts before the court.
Instead, he applied a singlet and duct tape over the wound he inflicted as she blocked the door to the bedroom where her friend was dying.
Ms Millward submitted the makeshift bandage application was not motivated by remorse.
"He said part of the reason he wanted to keep her alive was to have sex with her," Ms Millward submitted.
The crime appeared to have a "sexual component", and while not suggesting it was the motive, she said it could impact Kovaleff's prospects of rehabilitation and whether he was genuinely remorseful.
Mr Evers submitted Kovaleff not killing the second girl, and his early guilty plea, both showed remorse.
Justice Stephen Rothman will consider both submissions before delivering a sentence on March 10.
Kovaleff sat silently in the dock on Wednesday, spending large portions of the hearing staring at the carpet.
