Australian says he shot woman after aliens told him to

An Australian man shot at his former girlfriend inside a Sydney casino after aliens told him to, a court was told.

Todd William Devaney pleaded guilty to shooting fitness instructor Holly Graham while she taught yoga at Star City casino's gym in May 2008.

Graham suffered serious wounds but survived, AAP news agency reported.

Devaney's psychiatrist Rosalie Wilcox told the court her patient was suffering from untreated paranoid schizophrenia at the time of the incident.

Devaney had heard voices and taps on the casino wall that he interpreted as coming from aliens, Wilcox told the Downing Centre court.

"He's talked about that before... he's talked about aliens. It's certainly something he talks about when he's unwell," she said.

Wilcox said Devaney interpreted the messages as coming from aliens and decided to shoot the woman.

She said Devaney's illness was being treated and his prospects of rehabilitation had improved.

In a victim impact statement read to the court by her father, Graham said she still lived in fear of Devaney.

Devaney had pleaded guilty in July 2010 to intending to murder the fitness instructor. He had shot Graham twice below the hip and ribs.

He fled the scene but was arrested later wearing a fake moustache and beard, a latex mask, carrying three pistols, a folding knife and two apples.