Mark James Dennis, of Tregear, in Sydney's west, pleaded guilty in March to 13 charges, including having sexual intercourse without consent, armed robbery and maliciously applying an explosive substance. During sentencing submissions in the NSW District Court today, the court heard how Dennis robbed, then raped the woman in front of her toddler as they walked home after Carols by Candlelight in Liverpool five years ago.

Dennis robbed the woman at knife point and threatened to hurt her son, telling her, "Maybe I should take you for a drive but I guarantee that if I take you for a drive that it will be an all night thing because I have some friends in a car and they aren't as nice as me. Would you like a big gang bang?" He then raped her as her son watched, tied her hands and feet with rope, poured gunpowder into her eyes and lit it with a cigarette lighter. "You know you shouldn't cry 'cos it turns me on,'' he told the four-year-old as he masturbated in front of him.

"It's alright, I am the police and I am here to save you and mummy from the bad people that are going to drive by and start shooting. "I am going to lie on top of mummy and protect her.''

After raping the woman, Dennis poured a powder which he claimed was glucose into her eyes "so you can't see me walk away''. He ignited the substance, which was gunpowder, burning away her eyelashes and scorching the skin around her eyes. Judge Penelope Hock today described the use of gunpowder as a "completely gratuitous act which you might describe as torture''.

"I must say over 20 years of criminal law I have never encountered such an offence,'' she said. "It's not to have her subdued, she's already been subdued, he's already had sexual intercourse without her consent ... and then this act is performed.

"It's a completely gratuitous act of violence.'' Another of his victims, a 16 year-old girl, was walking home from school with her 10-year-old brother when Dennis lured them at knife point into a nearby park. He put his hands down the girl's pants and then forced her to masturbate him before tying her and her brother with their school ties and fleeing.

In both cases, semen found on the victims' clothing or at the scene matched DNA from Dennis's discarded cigarette butts. Wearing glasses and a dark suit, the former ice addict has gained weight since his arrest.

In a statement tendered to the court, one of his victims said she felt as though she had been unable to protect her son during the rape and had trouble dealing with knowing what he had witnessed. The other victim said her school work had suffered as a result of the attack. "It has affected me and will continue to do so for the rest of my life," the statement said. "I just hope that one day I can forget about it altogether."

Judge Hock ordered Dennis to undergo a psychiatric report before a sentence is handed down in November. - with AAP