The 22-year-old auditioned for the ITV1 talent series as a solo singer, but was convinced to form a group with Phoebe Brown, Leah Lauder, Emily Biggs, Charlie Mole and Raquelle Gracie after judge Louis Walsh suggested an "experiment" at boot camp, as seen in last night's episodes.
However, producers were forced to axe Sisi after discovering that she was wanted for failing to finish a community service stint. She had been convicted for assaulting a McDonald's worker, and chiefs feared that she could be arrested on live TV if police saw her performing on the show.
Sisi has also admitted that she smoked cannabis at boot camp, and claimed that other wannabes took harder drugs.
"I only did a bit of weed. There was a lot more than that going on and there's video tapes to prove it. I saw it all," she told the News of the World. "There were lots of drugs going round besides dope."
An X Factor spokesman said: "We weren't aware she was smoking cannabis and we wouldn't condone it. It shows we were right to get rid of her."