"When faced with a requirement to reduce his existing debt, Mr Johnston manipulated the system and submitted false sale and purchase agreements to his bank.
"The bank accepted the fictitious transactions," the SFO.
However, the properties were sold for a higher price than he stated or were transferred to another trust and refinanced with a loan from another bank.
In January 2012, Johnston submitted a false statement of assets and liabilities to the bank when obtaining the refinanced loan.
SFO director, Julie Read, said today the former lawyer had breached his professional duties and deceived the bank for personal gain.
"The first decision to take a dishonest path may seem insignificant but often means that there is no way back. Mr Johnston's decision left him in a far worse position, he failed to carry out his duty of care for his clients, he deceived the bank and now he will suffer the consequences of his actions."