Lee Smith, 20, shot Carolyn Lemm, 16, with a sawn-off shotgun then killed himself, just days after telling his victim's younger brother: "I'm going to kill her and dump her in the river", Sheffield Crown Court was told.

As the horror unfolded, Carolyn's terrified friend ran for her life to a nearby farm in a village near Rotherham, where police were alerted and found Smith's alleged accomplice slumped drunk in a car sobbing over the deaths.

The details of the double shooting on December 13 last year near the village of Woodsetts unfolded for the first time yesterday as Smith's friend Adam Briggs, 20, went on trial for murder.

Prosecutor Peter Kelson QC said the couple had been together for several months, but split up and Smith took it badly. He stole the gun from his mother's home in Saltfleet, Lincolnshire, the day before and drove to Sheffield in his Fiat Punto with Briggs.

They picked up Carolyn and her 17-year-old friend, who cannot be named for legal reasons, in Sheffield city centre before driving out to Woodsetts late in the evening. The 17-year-old told police she and Carolyn met up with the men and Smith said he had £4,000 stashed in the countryside.

Briggs got out at a layby and went to get something which he passed to Smith, who then ordered both girls out at gunpoint. They were forced to walk up the track away from the road and their mobile phones taken.

Mr Kelson said: "Briggs told (the 17-year-old) she had better run for her life as he was using the gun after Smith had used it. The girl did run, and she ran and she ran and she heard a gunshot as she ran."

Briggs, formerly of Swallownest, Rotherham, who was living in Lincoln at the time, was originally arrested on suspicion of double murder and was found slumped and drunk in the driver's seat of the car. Police had to smash a window to gain entry and Briggs began sobbing uncontrollably. He said: "I had only come with them to show them Sheffield."

Briggs told police Smith showed him the gun on the way to Sheffield and they stuffed it in a rabbit hole near the alleged murder scene before continuing to Sheffield.

At Woodsetts, Smith found the gun and told Briggs: "Stay there or I will do you and all." He made the two girls get out of the car and walk up the track. Briggs said: "I had to go back. They were asking me to help them. I just had to walk away. I couldn't do nowt. I heard a bang and couldn't see anything. I couldn't hear any screams. I just drank whatever was in the car."

Mr Kelson said it was unusual for Briggs to be charged with murder as he did not pull the trigger. But he helped secure the weapon, carry out a test firing and helped hide the gun and encouraged Smith to carry out the shooting.

Mr Kelson added: "Briggs was well aware that Smith harboured grave ill-will towards Carolyn Lemm. He chose nonetheless to help him carry out that ill-will using the sawn-off shotgun.

"For whatever reason and motive he gave assistance and encouragement to Lee Smith in carrying out an enterprise which he realised may involve the shooting and killing of Carolyn Lemm."

In a video interview with police shown in court, the 17-year-old girl said: "He told me to get out of the car and started pushing us and he hit Carolyn on the back with the gun. Then he got the gun near my head and he said 'If I don't run he was gonna shoot me.

"Lee said to me 'Run, just run for your life or I'm gonna shoot you' but I heard two shots – shots, one like when I were there thinking it hit the floor and then one when I ran off. I turned around and my friend was on the floor."

She went on: "I thought I was gonna get shot, I thought I was gonna die." She said Carolyn felt the same. She whispered to Carolyn "Carolyn we're gonna die" and she replied: "I know."

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