Dr Teo is facing a second day of disciplinary hearings in Sydney over allegations including that he did not sufficiently inform patients of the risks of surgery.
Two witness statements by Amit Goyal were dissected at the NSW Health Care Complaints Commission's Professional Standards Committee inquiry on Tuesday.
An initial statement by Dr Goyal to the commission in 2019 differed greatly to a second statement, drafted by Dr Teo's lawyers, in the amount of detail it recalled Dr Teo providing to a patient and her husband.
The patient in question never woke up from her surgery, with her husband telling the commission on Monday they were driven by desperation to consent to her going under the knife.
Dr Goyal told the commission in 2019 he was in the room with Dr Teo and the couple for two to three minutes while the risks of the surgery was explained to the couple.
"Charlie didn't go into a lot of detail with (the patient and her husband) while I was in the room," Dr Goyal's statement said.
"However, I do specifically remember him emphasising how risky the surgery was ... and there was a chance the surgery could leave her in a vegetative state."
In his second statement, Dr Goyal recalled a far greater level of detail regarding risk being conveyed to the patient and her husband, including a "significant risk of adverse outcome".
The commission's counsel told the hearing the second statement described a process that could not "physically" have happened in the few minutes Dr Goyal said he was in the room.
"You have the second witness statement with a whole plethora of risks and nuanced analysis," Kate Richardson SC said.
"The number of things he remembers Dr Teo discussing could not happen in that time."
She said the second statement had "emerged or been elicited" through contact with Dr Teo's lawyers and that Dr Goyal had been "contaminated" as a witness by contact with Teo's lawyers.
Dr Teo's barrister, Matthew Hutchings, argued there was "no material inconsistency between the two documents".
Dr Goyal said some of what he had written in his second statement could have come from later one-on-one discussions with Dr Teo in which he relayed what he had told the patient and her husband.
"Are you suggesting there are parts of this witness statement you did not hear Dr Teo say to the patient?" Ms Richardson asked.
"Yes," Dr Goyal replied.
Dr Goyal was one of 30 neurosurgeons who signed a statement of support for Dr Teo in 2021 when the complaints against him first emerged.
The statement described Dr Teo's commitment to teaching, research, and patient care as "the highest quality".
Ms Richardson asked Dr Goyal if he is a supporter of Dr Teo, to which he replied "yes".
Dr Teo was restrained by the NSW Medical Council in August 2021 from operating without the approval of another doctor after an investigation by the commission.
The 65-year-old is famous for performing neurosurgery on cancer patients with tumours other doctors have deemed "inoperable" but has been accused of charging exorbitant fees and offering some patients false hope.
He has been banned from operating unless a second doctor is satisfied his patients are aware of the risks and are financially informed about their decision.
Dr Teo has consistently denied any wrongdoing.
The inquiry, overseen by Judge Jennifer Boland, is expected to run until Friday.
