Social Development Minister Paula Bennett has released two letters she wrote in relation to Viliami Halaholo.
Halaholo is the boyfriend of her 21-year-old daughter and the father of Ms Bennett's two-year-old granddaughter, and is serving time in Mt Eden Prison.
He was a member of a youth gang and was bailed to Ms Bennett's address in Titirangi while on remand on charges of wounding with intent in a gang fight. He was jailed for four and a half years.
Ms Bennett was an opposition MP at the time. The letters written by Ms Bennett were to the judge in 2007 and the Parole board in 2008.
She told the judge Halaholo had turned his life around.
She told the Parole Board that with her support she was sure he would never be before the courts again.
The Prime Minister says he is disappointed he was not made aware of the release the letters.
Mr Key says a week before the letters were released he had asked Paula Bennett about issues relating to Halaholo.
But he says he accepts no deliberate attempt was made to mislead him.
Halaholo was jailed for causing grievous bodily harm, but his girlfriend - Bennett's 21-year-old daughter Ana - visits him once a fortnight in Mt Eden Prison.
Police said Halaholo, 23, was a member of the Thugs of Canal, a so-called youth gang based around Canal St in Avondale.
The gang members reportedly have a history of violence and intimidation, creating the risk inappropriate pressure could be brought to bear on the senior minister and her decisions.
Halaholo left Avondale College aged 17 and got work with a road crew. He had been in regular police trouble because of his involvement in up to 10 fights, his father Lolo Halaholo said.
Halaholo's aunty, Tolo Langi, said her nephew had settled down after meeting Ana, but had still hung around Avondale with his gang associates.
Ana studied at Excel Ministries School of Performing Arts before becoming a mum.
Ana and Halaholo plan to set up house with their child and Halaholo's other toddler daughter when he gets out, Langi said. The family hoped he would be up for parole this year.
- NEWSTALK ZB, NZPA, NZ HERALD STAFF