Being behind bars was not enough to stop a man serving time in Wanganui Prison from threatening a 13-year-old girl using the prison's pay phones.
The man, who was already serving time for violent offences, was sentenced in Wanganui District Court this week to a further one year and three months in jail.
The harassment became apparent when police accessed the man's calls after receiving a complaint from the girl's mother who was the ex-partner of the prisoner, the Department of Corrections said.
"He had said to the girl that he would hurt her mother if they didn't leave Wanganui, and she was considerably distressed by his threats," the department's intelligence manager, Dave Alty, said.
"The introduction of telephone monitoring technology in 2008 to every prisoner pay phone in New Zealand meant that we had a recording of the prisoner's call, and could confirm that he had been making threats to the child," he said.
"We acted immediately to have the victim's phone number removed from the prisoner's approved calling list and passed the recording on to police who were able to charge the man with threatening to kill."
The use of random telephone monitoring allowed the department to detect offending and pass important information on to police, Mr Alty said.
