Catterall's lawyer, Marcus Edgar, outlined his client's descent into drug addiction, crime and depression. Meth, he said, seemed to give Catterall an escape from domestic difficulties. "It would make her feel anaesthetised," Edgar said.
To pay for her increasingly costly habit, Catterall began forging chief executive Charles Anderson's signature on fake invoices, which she would have processed at the Sovereign accounts department.
Edgar said underworld figures recognised Catterall was "a middle-class woman with a respectable job" and had access to money through her work. Meth dealers, he said, manipulated her into paying more and more for smaller and smaller doses of the drug.
Soon, thousands of dollars were siphoned to accounts of "third parties", some of whom now also face prosecution. In total, Catterall defrauded Sovereign of $643,000 from October 2011 to January last year.
Catterall, now 36, had no prior convictions, and pleaded guilty at an earlier case review.
Judge Roy Wade said the law gave him no alternative but to send her to jail.
"There are occasions when there is no job satisfaction at all in what I do," he said. "This is one of those occasions."
The judge sentenced Catterall to two years and nine months in jail on three charges of using a forged document for financial gain.
Sovereign has recovered about $30,000 after working with commercial lawyers Simpson Grierson. Civil proceedings, to which Catterall has consented, could recover more cash. Judge Wade said total losses to Sovereign were around $1m, including company investigations and other expenses.
Several of Catterall's supporters and relatives were in court. Some tearful, they consoled one another as it became clear Catterall would be sent to jail.
Judge Wade said Catterall was due to complete a rehabilitation course in one week but there was no point delaying her term of imprisonment. "The sooner you start it, the sooner you will finish."
