A South Australian man who sexually abused his sister and two of his daughters in what a judge said was "manipulative, cruel and malevolent" behaviour has been jailed for 20 years.
The man, 62, who cannot be identified, first abused his sister in 1978 when she was just five years old and continued that abuse until she was aged about 12.
He also allowed his friends to sexually abuse the girl, District Court Judge Joanne Tracey said in sentencing remarks published on Thursday.
"You warned her not to tell anyone in a most horrifying way, on one occasion taking her out to the shed with her watching as you slit open a pet guinea pig, telling her that that was what would happen if she told your parents," Judge Tracey said.
The man's offending against his daughters began when one was aged about four and when the other was aged about nine.
Judge Tracey said on one occasion he had told one of the girls that "God had made her to be like a wife for you".
"It is hard to imagine how terrifying, frightening and confused each of those little girls would have been," the judge said.
"You offended against your own sister when she was a very young child and you were an adult. It spanned seven years.
"Years later you proceeded to offend against two of your own biological daughters.
"Your behaviour towards each child was manipulative, cruel and malevolent."
The man pleaded guilty to maintaining an unlawful sexual relationship with his sister and to maintaining an unlawful sexual relationship with one of his daughters.
He was found guilty at trial of seven sexual offences against his other daughter.
Judge Tracey jailed him for 20 years with a non-parole period of 16 years.
Australian Associated Press