Raenette Yangson was sentenced to three years in federal prison yesterday after it was discovered that she had embezzled more than $750,000 from her employer. She worked for Western Construction and Equipment in Anchorage, Alaska, and it took a bizarre turn of events to bring her to justice.

In an interview with Anchorage Daily News, company owner Jeff Light describes how he caught Yangson.

She worked as a bookkeeper from 2006 to 2013 and court documents show she wrote 405 forged checks to herself and her husband which amounted to $753,000. After writing the checks, she would go into the accounting system and edit them to make it appear as though they were legitimate payments. This went on for years and was not even discovered by IRS audits.

One day, Light's grandson accidentally installed a virus on his home computer. Since it was also connected to the business network, it had online access to the accounting software. The virus would not let Light sign out of the system which in turn prevented Yangson from using the "single-user" mode. She had been using this to manipulate the books without anyone else noticing.

Since she was no longer able to edit the payments, she decided to try and balance the books by writing off the discrepancies as a certain type of industry fee. Light discovered these fees and since Yangson had used the wrong type of fee for the time period, he immediately knew something was up and launched an investigation.

Yangson has been ordered to pay restitution with the amount still to be determined. On top of that, she must also pay the IRS over $200,000 in taxes for the money she stole.

These subtle financial crimes often go unnoticed unless the criminal makes a mistake. This is one of the few cases where a computer virus ends up doing more good than bad.