One of Scotland's youngest killers has been found dead in custody at HMP Castle Huntly.

Thomas Shields was 15 when he murdered James Herd, 27, at a Glasgow bus stop in Glasgow in March 2003.

The High Court in Edinburgh heard Shields hit Mr Herd with a metal pole and jumped on his head "like a trampoline".

Both men lived in Garthamlock in the north east of the city.

Lord Hardie described it as a "vicious, brutal, persistent and unprovoked" attack on an innocent man.

The killer was jailed for life in March 2004 and ordered to spend a minimum of 18 years in prison before he could apply for parole.

The Scottish Prison Service confirmed Shields, 30, died while he was in custody at the open prison in Dundee.

A Scottish Prison Service spokesman said: "Police Scotland have been advised and the matter will be reported to the procurator fiscal.

"Next of kin have been informed and a fatal accident inquiry may be held in due course."