The man, who can only be referred to as MM, was arrested in October 2011 after it emerged he had been raping his stepson since the boy was  six years old, forcing him to engage in sexual acts ‘‘about once a month’’ since 2001.

MM also abused his stepdaughter at the same time, coming to treat her like his girlfriend when she was 16 and 17, and claimed they had spoken of running away together.

He also molested his own daughter in  2011, when she was 10 or 11.

Wollongong District Court judge Paul Conlon sentenced MM to 20years’ jail with a non-parole period of 15 years in November 2013, after hearing harrowing victim impact statements from the siblings, then aged 18 and 21.

The sentences were reduced on appeal to 17 years and 12 years respectively, after it was agreed Judge Conlon had made a mistake in not reducing the individual sentences on two  of the charges in which MM had made voluntary admissions to the conduct.

However, the  panel of  justices Anthony Meagher, Carolyn Simpson and Monika Schmidt was not unanimous in its decision, with Justice Schmidt the dissenting voice.  She  found that though the  sentence was ‘‘stern’’, it couldn’t be considered too excessive given MM’s ‘‘long pursued course of criminal conduct’’.

The  abuse of  the boy  came to light when he spoke to his mother  in March 2011, shortly after leaving a suicide note on his bed.

He later told the court of the deep torment he had felt at the hands of his stepfather.

‘‘He was meant to be my new father when my parents split but instead he made me wish I was dead,’’ the boy said.

‘‘He made me his prisoner ... I’ve lost count of how many times I almost killed myself.’’

His sister told a neighbour about the sexual relationship between herself and MM in September 2011.

MM later described the nature of their relationship to police during an interview.

‘‘We’d kiss and cuddle and, you know, go places together ... have sex,’’ he said.

‘‘[We’d] have sex from once to four times a week.’’

However, the girl told the court she’d felt controlled ‘‘like a robot’’ when she was with him.

‘‘As long as he was pleasured [that] was all that mattered to him,’’ she said.

‘‘I was treated and abused like a sex toy, it seemed like a game to him.’’

With time already served, MM will be eligible to apply for release on parole in October 2023.