'Greedy' assistant stole $471k from boss

She was a trusted personal assistant who had known her boss for 15 years but that didn't stop "greedy" Leigh Isabella Black from stealing almost $500,000 from his company.

And when the 35-year-old was finally caught and confronted by her employer she said she had only stolen the money because she was being blackmailed and bikies had threatened her family.

This was a complete lie. In fact, Black used the cash to buy three properties.

Now the South Australian will spend at least two-and-a-half years in prison after she was sentenced for 42 counts of theft.

Black, of Springton, was trembling and in tears as Judge Paul Muscat handed down a maximum jail term of four years and fine months on Thursday.

"You were implicitly trusted," Judge Muscat told the South Australian District Court.

"You exploited your position of trust and authority for your own greedy benefit."

Black, the court heard, transferred more than $471,000 from the Mitolo Corporation's bank accounts into three accounts of her own between January 2013 and November 2014.

She was caught because she left a folder on the company's server containing evidence of the clandestine transactions - a folder her boss eventually discovered.

"When he produced to you the banking statements you suddenly became speechless and nervous," Judge Muscat said.

"You claimed that people were chasing you - that you were being blackmailed over debts and that your life and the lives of your family had been threatened by bikies.

"This was nothing more than a lie."

Black's boss, upon learning she had bought several properties with the money, drove his assistant to the police station.

She later accepted full responsibility for her actions.

The court heard Black was once an elite sportswoman but this career had been cut short because she had developed the chronic autoimmune disease lupus.