Cape Town - A former Western Cape relationship manager at Barclays Wealth, a division of Absa, was found guilty on Monday of 39 counts of theft involving R15m.
John Julyan was also convicted of money laundering by the Bellville Specialised Commercial Crime Court.
Magistrate Amrith Chabilall set down sentencing proceedings for December 2.
Julyan had been out on warning.
Asghar Mia, for Julyan, asked the court to either extend the warning, or to release him on bail of no more than R2 000, which was all that Julyan would be able to raise.
Prosecutor Juan Agulhas said Julyan should be kept in custody until the case resumed.
Chabilall said the circumstances, as of Monday, had changed drastically from the stage when Julyan was presumed innocent.
He told Julyan: "You have been found guilty of theft involving R15m and that, in anyone's language, is a huge amount.
"You will be kept in custody until the case resumes."
As a relationship manager, Julyan was responsible for multi-million rand investments belonging to Absa client the late Professor Bryan Cremin, who prior to his death was the head of radiology at the Red Cross Children's Memorial Hospital in Cape Town.
The professor suffered from Alzheimer's Disease and became unable to manage his affairs while Julyan was in control of his investments.
Julyan stole Cremin's funds to purchase fixed property in Knysna, on the Cape south coast, and in the upmarket Cape Town suburb of Constantia.
Julyan also pumped Cremin's funds into a financially troubled business owned by Julyan's wife, bought a boat that he moored at Knysna, and went on expensive holidays to Austria with his wife.
Julyan also paid his own mother exorbitant amounts for the drafting of a will, from Cremin's funds.
Chabilall told Julyan: "If it can be said at all that your defence presented a cogent defence to the charges, it disintegrated with your own testimony."
Chabilall said Julyan was "at best" a pathetic witness when he testified in his own defence.