The trial of seven people accused of murdering a man in Dublin has heard their alleged victim was left for dead after being subjected to a "vicious attack".

Dale Creighton (20) died in hospital from serious injuries to the head and face on January 2nd, 2014 – a day after the alleged assault.

This afternoon, the jury was shown CCTV footage from a footbridge over the Tallaght bypass. It was taken just before 4am on New Year's Day 2014.

Gardaí believe Mr Creighton was chased there after a girl claimed her phone had been stolen.

In his opening address for the prosecution this morning, Seán Gillane told the jurors that a security camera had captured part of the incident on the bridge.

He told them that they would be satisfied that Mr Creighton was attacked while he was defenceless on the ground and at times while he was being held up so he could be punched and kicked.

Mr Gillance said the young man was then dragged to the steps like a "rag doll" and thrown down them while being shouted at.

One witness said she saw the violence from her balcony. 

Another said he saw one person sitting on top of the steps with his legs dangling below. 

He said he looked like he was in trouble because he was not moving.

The six men and one woman on trial all deny his murder and have also pleaded not guilty to violent disorder.

The seven accused are: David and Aisling Burke, a brother and sister who live at Beechpark in Collinstown, Co Westmeath; Graham Palmer, currently of Park Avenue in Portlarlington, Co Laois; Ross Callery of Gortlum Cottages in Britas, Co Dublin; James Reid of Glen Aoibhinn, Gorey, Co Wexford; Jason Beresford, Castledermot Co Kildare and Gerard Stephens who has an address at Grosvenor Square, Rathmines in Dublin.

The trial is expected to last at least six weeks.