David Witchall, 34, is serving a sentence of more than nine years but at a hearing last month the Parole Board questioned whether there had been a paperwork oversight.
"The board is a little confused about the length of sentence which Mr Witchall is now serving," panel convener Serina Bailey said.
In November, Witchall had 19 months added to his jail term — taking the notional total to more than 11 years — for an attack on another inmate, but his record did not reflect that.
In March, while serving his time at Christchurch Men’s Prison, Witchall and another gang member were in the high-security unit.
The defendant was in a storage locker and called the victim over.
He was followed by Witchall’s 44-year-old co-defendant, who punched him from behind, rendering him unconscious.
"The victim regained consciousness as both defendants were stomping and kicking his head and body," court documents said.
The victim was left with a fractured cheekbone and nose, and severe bruising around both eyes.
In 2015, Witchall was locked up on a variety of sex charges against young women.
He met a 16-year-old through a mutual friend and became angry when she refused a hug.
He led her to a basement carpark and said she could only leave once they had sex.
He was also convicted of grooming four under-16s.
Witchall bombarded them with messages until they agreed to meet, and when they did, he molested them.
While he had "little to say" at his most recent parole hearing, he continued to deny responsibility for the sex crimes.
Because of that, he was not deemed suitable for specialist rehabilitation.
He was, however, amenable to an anti-violence programme.
"The board believes this is appropriate in light of his history and particularly his most recent convictions," Ms Bailey said.
The treatment was expected to begin in the coming months.
Witchall continued to have no proposed accommodation or release plan before the Parole Board.
He will next be seen in December.
rob.kidd@odt.co.nz , Court reporter
