She was educated at the University of New South Wales, graduating in social work, and was a community worker running the Hillsong Church's drug and alcohol outreach service in Blacktown prior to entering politics.
[1] Subsequent to the 2004 election, unsubstantiated allegations were made in the NSW Parliament under parliamentary privilege that Markus had directly benefited from unauthorised campaign materials containing false statements in an attempt to capture anti-Islamic sentiment against her Labor opponent.
[4] At the 2007 federal election, Markus retained the seat of Greenway with a comfortable margin, although with a nominal swing of 6.85 points against her on a two-party-preferred basis.
[7] Markus contested the 2010 federal election as the Liberal candidate for the seat of Macquarie, which had absorbed a fraction of her former electorate base.
[9] At the 2016 federal election, the incumbent Markus lost the seat of Macquarie to three-time challenger, Susan Templeman.