The man armed with a semi-automatic gun who strolled through the Bourke Street Mall in the days following the January massacre is a former VFL player who was sacked by a security company last year.

Security guard Aaron Purvis – who was not registered to work as a guard nor licensed to carry a firearm – is expected to be charged with a weapons offence after the troubling security breach.

Aaron Purvis is a former VFL player. Credit:Aaron J. Purvis/Facebook

Mr Purvis' Facebook page shows images of him posing in front of the mirror and includes the quote: "When life gives you lemons, ask for something higher in protein."

It is understood he was not hired to guard Bourke Street on the day he was seen but was rostered to work a security shift nearby.