A man jailed for life for murdering a Southland teenager and dumping his body - wrapped in a mattress and weighted down with heavy bars - in a river, will stay behind bars after a failed parole bid.
And for the first time he has explained why he killed the teen he had "befriended".
In 2008 Christopher Wayne Patterson was sentenced to life imprisonment with a minimum non-parole period of 13 years for the murder of 18-year-old Michael Hutchings.
The teenager's body was found in the Clutha River near Kaitangata on January 12 in 2008.
He had knife wounds in his neck and stomach.
Patterson's de facto partner Nichole Field was sentenced to two years in prison for being an accessory after the fact of Hutchings' brutal murder.
In court the offending was described as premeditated and calculated - but no motive was established.
But when Patterson, now 50, appeared before the Parole Board last month he finally gave insight into the killing.
Parole Board chairman and panel convenor Sir Ron Young said Patterson murdered Hutchings after befriending him.
"The circumstances of the murder are somewhat unusual, and we spent some time talking with Mr Patterson as to the reasons behind the murder," said Young in his decision released to the Herald today.
"Currently his explanation is, as we understand it, as follows. The young man that he killed had a car accident. In the accident a young boy was hurt.
"The father of the boy was apparently a gang member. Mr Patterson said he became concerned that the young man would be killed by the father of the boy in retribution for the injury from the car accident.
"The young man was therefore encouraged to go to Australia however the plans did not
work out and he returned to be with Mr Patterson and his partner."
Young said Patterson told the board his partner "convinced him" that he either had to kill Hutchings or be killed himself "in substitute".
"And so it was a case of him or me and so Mr Patterson killed the young man.
"The explanation given by Mr Patterson as to the reasons for the killing are certainly strange… In our discussion with him, he did acknowledge the strangeness of the circumstances and motive for the killing."
Patterson told the board he accepted he needed to complete further programmes in prison and then be reviewed for any further drug treatment courses.
"We note that he does appear to have had a significant history of, at least, alcohol abuse," said Young.
Further psychological assessments were also requested if deemed necessary after medical testing for an issue related to injuries Patterson suffered in two motor vehicle accidents.
"In the meantime, Mr Patterson remains an undue risk.
"We will see him again by the end of August 2022."
Before the parole hearing the board met with Hutchings family.
"They opposed his release on parole," said Young.
"Mr Patterson's response was that he could completely understand why they would not
wish him to be released on parole."