Ewen Macdonald - the man acquitted of killing Scott Guy - has been released from prison on parole.

Macdonald has been behind bars since April 2011 when he was arrested for his brother-in-law Scott Guy's murder.

He was acquitted at a high-profile trial a year later but jailed for five years after admitting a string of other offences, including burning down Mr Guy's house, vandalism and killing 19 calves with a hammer.

A Corrections spokesperson confirmed Macdonald was not in custody.

"He's no longer in prison," she said.

Corrections would not comment further.

The sister of Mr Guy's widow Kylie, Chanelle Bullock, wrote on the Lets do it for Scotty Tribute page on Facebook that today was "the day that we wish never would happen".

She said Macdonald had been released from Christchurch Prison.

Macdonald met the Parole Board on October 16 to ask for early release for the fourth time.

His first bid for freedom was at Manawatu Prison, the last three at Rolleston Prison, near Christchurch.

Last year, the board decided Macdonald still posed a risk to the public. He had previously been described by as having "a significant personality disturbance".

While finding he no longer posed a risk, the board's decision imposed strict conditions on Macdonald for the six months after his release - including GPS monitoring, banning him from the North Island and stating he could not possess, own or use firearms, ammunition or restricted weapons.

He was also forbidden from contacting co-offender Callum Boe, a former worker on the Guy family farm, and must stay home at night.

He has a job and somewhere to live and the board says he's supported by friends and family, as well as professionals.

The panel that met him said at the time Macdonald was now seeking advice from others, which he had previously found difficult.

"He has practiced letting things go rather than holding grudges and ruminating about perceived wrongs.

"Importantly, he has also begun to share his feelings of frustration or sadness with others in prison and with members of his family."