A magistrate has described letters written by an inmate to a female prison worker as "depraved" and "despicable", as he sentenced the man to a further three and a half years in prison.
Magistrate Gregory Robinson also put Wayne Patrick Clancy, 59, on the sex offenders register for life.
Clancy is currently serving a sentence for rape and has a murder conviction.
Sentenced in person at the Ballarat Magistrates' Court after pleading guilty, Clancy was charged with three counts of threatening to commit a sexual offence.
In May, the court was told Clancy had written three obscene letters to a female prison worker, one of which she found, which caused her to have a mental breakdown and eventually leave her job at that facility.
The court was also told Clancy had endured a "tragic upbringing", having been institutionalised since he was three-years-old.
His defence lawyer noted Clancy had "very little exposure to the outside community".
However, while Mr Robinson said he took that and the guilty plea into account, the letters were "like something from a horror film".
"If I or my family received these photos during my employment - I don't think there's any exaggeration in the victim's response," he said.
"How does she hold herself together in those circumstances?
"She's devoted her life to helping men like the accused and she gets these abhorrent letters.
"It could be more serious - but nevertheless, they're sinister, they're scary, and something she'll never forget for the rest of her life, and I don't think I will either."
Clancy is due for parole in June next year, however Mr Robinson agreed that the charges were serious enough to alter the date.
The three and a half year sentence includes a two year and two month non-parole period.
Mr Robinson added the "paramount consideration" was the safety of the community.
Speaking directly to the accused, he said Clancy's background did not excuse the harm he had done to others.
"It's depraved, despicable, and would lead anyone objectively to be fearful and crushed to see another being treat them that way," he said.
"I am concerned if you had the means to carry out what you threatened, what would be the result.
"The best place, for the community, is for you to be in prison.
"On behalf of the community and victim, I denounce your conduct, and without hesitation I impose that sentence on the basis you are a serious sex offender and threat to the community."
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