The Australian actress, who plays Loretta Schembri in the television drama, said that she tried not to pin too many hopes on winning the role when she went back to audition in front of the producers.
Marshall told National Features: "I had about five or six callbacks during auditions. I tried not to think about the fact each time I went in, I was getting closer to the role. But honestly, the last thing I expected was to be cast.
"When I started, Jess [McNamee] had finished filming and I learnt later that Zoe [Ventoura] was planning to leave, but none of us had any idea how she would leave. When we had the read-through of the episode when she actually died it was devastating."