A former Sydney floor trader has "unreservedly apologised" to the bank staff he threatened during a spree of robberies more than 40 years ago.
"It was such a shameful period of my life," Ross Oliver McCarty said in the NSW District Court on Thursday.
The 71-year-old was giving evidence at his sentence hearing, after admitting to leading a "double life" in which he would "get boozed at lunch time" and rob banks.
He has pleaded guilty to four robberies and asked the judge to take into account another four crimes which took place over a 10-month period in 1977 and 1978
Advancements in fingerprint technology led to him being arrested at his Edgecliff home in 2018.
On Thursday he read out a letter addressed to those he had threatened while demanding cash.
"My circumstances at the time made it easy for me to delude myself into believing my appalling actions were justified," he said.
He had ridiculously believed that the use of polite words like "thank you" would send signals that "I really didn't mean any harm".
After many years of causing obvious collateral damage to his friends, family and colleagues, McCarty said he could only imagine the terror he caused his victims through his "wanton egoism".
"I truly hope you have been able to recover from the trauma I inflicted on you many years ago," he said.
McCarty told Judge Sarah Huggett he had illegal gambling debts at the time and received threats of violence at his work if he didn't repay them.
After his arrest, he decided to "make full and frank admissions" to police, including by confessing to an armed robbery with which he had not been charged.
"It was an opportunity to rid the demons," he said.
McCarty, who was in his late 20s at the time, carried a water pistol and wore various disguises including sunglasses and moustaches.
He produced hand-written notes on withdrawal slips, warning tellers he was armed and demanding they hand over cash.
If he could face his victims now, he said he would offer his "absolute heartfelt apology and ask if there is anything I could do to make amends".
He had abstained from alcohol since 1989, stopped gambling many years before then, began medication for previously undiagnosed ADHD and had undertaken volunteer work.
His barrister described the case as "exceptional", submitting that a community penalty could be imposed, while the prosecutor said the only appropriate penalty was jail.
McCarty has previously served time for fraud offences.
He will be sentenced for the robberies on September 18.