Rotorua truck driver Anthony Doyle murdered an Omokoroa couple who were settling a drug debt because he thought he was being set up.

Doyle, 40, pleaded guilty in the High Court at Rotorua yesterday to two counts of murder. He had previously denied shooting Michael Douglas O'Sullivan, also known as Mikaere O'Sullivan, and his partner Toni-Anne Nathan execution-style last October at the Wairoa Bridge near Tauranga, where the trio met to conduct a drug deal.

Doyle had told an associate he had Mr O'Sullivan "squealing like a pig, begging for his life" before he killed him.

The relationship between the trio had turned sour after the couple incurred a $5000 methamphetamine debt.

Mr O'Sullivan and Ms Nathan had been wary of Doyle, a heavy user of methamphetamine, or P, and had been excited about the prospect of repaying their debt and severing ties with the Rotorua man.

A police summary of facts stated the victims had been avoiding contact with Doyle because the debt had caused the relationship to become heated and volatile and they feared retribution.

The day before they were killed, the couple went to Auckland and bought more than 9g of P. The drug can reach prices of $1000 a gram but when bought in bulk the amount can be reduced to half that.

The couple were to meet Doyle at 3am on October 31 under the Wairoa Bridge to finally settle their debt.

Before leaving Rotorua to meet them, Doyle armed himself with a sawn-off double-barrelled shotgun. He loaded it and took at least five other live cartridges with him and on the way to Tauranga fired a test shot into the forest to make sure the gun was working.

Doyle told police that when Mr O'Sullivan and Ms Nathan arrived he saw the P and scales in the console of their car and although not physically or verbally threatened, he suspected he was being set up.

He went to his car and got the shotgun and shot Mr O'Sullivan once at close range in the chest, killing him. Doyle then shot Ms Nathan because she was trying to start the car and drive away.

He shot her in the shoulder, then had to reload before pointing the gun at close range at her right cheek and firing again.

The couple's bodies were found at 6.15am.

Doyle was arrested on November 6 after his Konene St, Rotorua, home was surrounded by the police armed offenders squad.

He co-operated with police by showing them where he hid the gun and remaining ammunition. The methamphetamine bought in Auckland by the victims "mysteriously disappeared", according to the summary of facts.

Mr O'Sullivan's children were in the courtroom yesterday and broke down in tears when Doyle pleaded guilty to the two counts of murder.

The police officer in charge of the case, Detective Senior Sergeant Greg Turner, said family members were relieved Doyle had accepted responsibility.

Justice Geoffrey Venning convicted Doyle and remanded him in custody until sentencing on October 13.