He allegedly told his partner his wealthy mother was "in the way" and her friend "knew too much".
"I had to get rid of them," Sydney cosmetic surgeon Dr Jerry Schwartz told his now ex-partner Liliane Viselle in 2005, Glebe Coroners Court has heard.
But while finding Dr Schwartz often gave "unbelievable, vague or evasive" evidence at an inquest into the deaths of his mother - hotels matriarch Eve Schwartz - and her friend Magda Wales, NSW State Coroner Mary Jerram said there was not enough evidence to refer the matter to the Director of Public Prosecution (DPP).
"No one could be untroubled by what we have heard," Ms Jerram said in her findings handed down on Friday.
"At the very least ... the two deaths should each have been reported to the coroner so that autopsies could have been performed, possibly resolving the serious questions which have been raised in these proceedings."
The inquest heard Dr Schwartz signed the death certificates of both his mother and her close friend who were cremated after they died within a few weeks of each other in 2005.
The court heard Ms Schwartz, who was suffering from terminal cancer, had cuts on her wrists when Dr Schwartz discovered her body on August 21, but her death was not reported to the coroner.
Instead, Dr Schwartz put the time and date of death as being the last time he saw her alive on August 20 and listed the cause of death as lung cancer and a collapsed left lung.
When Ms Wales' body was discovered in her Rushcutters Bay home a few weeks later, Dr Schwartz's behaviour was "strange and aggressive", Ms Jerram said.
He tried but failed to gain entry to her apartment before he visited her body in the morgue and wrote a certificate saying she died of several causes including an acute cardiac event and obesity.
"He simply had no evidence to write a death certificate," Ms Jerram said, adding Dr Schwartz was not Ms Wales' doctor.
"What was the reason for his haste and fervour to do so, when Magda had in fact been recently seen by several other practitioners?"
Ms Viselle said when she asked Dr Schwartz how he knew to turn up to Ms Wales' apartment that night, he didn't answer directly but said, "My mother was in the way. Magda knew too much. I had to get rid of them."
Ms Viselle said he went on to say, "Prove it. I have had them both cremated. It will cost me less than $10,000 to get rid of you."
Dr Schwartz has strenuously denied these allegations.
The inquest also heard allegations Ms Schwartz was thinking of changing her will to include her estranged daughter.
Ms Schwartz and her late husband founded the Schwartz Family Company, which owns a dozen hotels in NSW and Victoria, a shopping centre, a medical centre and a brewery.
Dr Schwartz inherited the bulk of her estate upon her death.
Ms Jerram noted Ms Viselle was a "highly emotional" witness who was not always credible.
But she said overall the main facts Ms Viselle presented required examination and investigation.
Ultimately, Ms Jerram said many aspects of the evidence were "impossible to unravel".
She delivered open findings on the cause and manner of each woman's death.
And she referred Dr Schwartz to the Medical Council of NSW for possible professional misconduct in relation to the signing of the death certificates.
