Key Points:

A man who eluded police for 11 days in a massive manhunt in Northland after murdering his girlfriend has pleaded guilty.

In the Whangarei District Court, Black Power member Nathan Charles Fenton admitted killing his 17-year-old girlfriend Mairina Dunn in August.

Appearing for what was to be a deposition hearing Fenton, 31, also pleaded guilty to three charges of presenting a firearm at three people who witnessed the prolonged attack at 2 Holmes Ave, Whangarei on August 27 last year. Their names are suppressed.

He also admitted assaulting a man before he killed Mairina and charges of unlawfully taking a BMW and theft of camping gear and clothes.

Six other charges including burglary and theft were withdrawn.

Fenton's ex-partner, Eileen Verna Everitt, 29 also pleaded guilty to being an accessory to murder after the fact.

The police summary of facts said about 3am on August 27 Fenton arrived at the Otangarei address and accused the man of sleeping with Mairina.

He assaulted him before confronting Mairina who was asleep.

The summary said Fenton dragged Mairina from her bed to a balcony area of the house and confronted her with the same allegation which she denied.

He then "brutally assaulted" her beating her all over her body with a shot gun.

The initial attack lasted 90 minutes but it continued for several hours.

During the attack Fenton pointed the shotgun at three witnesses and threatened them not to say anything to police.

Mairina received numerous injuries including a fractured skull, broken rib and a punctured lung.

The summary said she most likely would have died as a result of massive head injuries or a puncture lung.

After attempting to clean up the scene Fenton fled the house about midday on August 27 and was on the run for 11 days.

On September 3 he met up with his ex-partner Eileen Everitt and continued on the run with her until the pair were caught at Otamure Bay on September 7.