A CONVICTED killer ran a £1million heroin ring from his prison cell.

Stephen Nisbet, 40, used a secret stash of mobile phones inside HMP Edinburgh to arrange drug deals across Scotland.

His businessman brother James Nisbet, 46, set a up a supposed recycling firm as a front to help flood the country with heroin.

But, the duo - along with a team of couriers - were snared when detectives swooped in January last year following Operation Lapstone, a seven month long surveillance operation by Police Scotland's Organised Crime and Counter Terrorism Unit (OOCTU).

It lead to the brothers being convicted of supplying heroin following a lengthy trial at the High Court in Glasgow.

Stephen Nisbet is already serving an 18-year sentence after being convicted of murder in 2003.

The killer faces another lengthy jail-term when he and his sibling are back in the dock next month.

A jury heard how Stephen Nisbet orchestrated a lucrative crime network despite being locked up in HMP Edinburgh.

Away from the gaze of prison guards, he had access to mobile phones with up to 10 different numbers.

This enabled him to set-up what prosecutors called "a family drug dealing business" between June 2013 and January last year.

His elder brother James formed a firm called Platinum Waste Solutions - close to the family cottage in Shotts, North Lanarkshire.

But, the trial heard this was a "front" to distribute heroin throughout the country.

Police soon got wind of the operation and watched as drug deals were carried out across Scotland.

James Nisbet was spotted meeting couriers. A number of arrests were made, but police continued their surveillance of Nisbet.

Co-accused Ronald Harrison and Allan Holland, 38, were also found guilty of being concerned in the supply of heroin although had lesser roles.

John McMahon, 27, David Milne, 34, and Robert Borland, 35, all earlier admitted to related drug charges.

The Nisbets and the other five were remanded in custody.

Judge Lord Armstrong adjourned sentencing until next month.

OCCTU Detective Chief Inspector Colin Boyle said tackling such crime was "a top priority for Police Scotland."