A murderer, detained for life for shooting dead a “thoroughly decent young man” in a Bradford park, has been given a further six-year sentence for threatening to kill a prison officer.

Feroz Khan, 26, was ordered to serve a minimum 20 years in custody in 2007 for the murder of university student Skander Rehman.

Skander, 20, was blasted in the back of the head at point-blank range by Khan in Brackenhill Park, Great Horton, with a semi-automatic pistol which had been converted to fire live ammunition.

Khan, of Cumberland Road, Lidget Green, Bradford, wrongly believed his victim had been having an affair with his wife. Sentencing him, Judge James Stewart QC described it as a “cold-blooded execution.”

Khan and another prison inmate also serving life for murder were yesterday sentenced to six more years each for threatening to kill the prison officer at a North Yorkshire jail, days after the murder of Fusilier Lee Rigby.

Feroz Khan and Fuad Awale, also 26, were found guilty at the Old Bailey last week following the incident at HMP Full Sutton on May 26 last year.

Khan was also convicted of inflicting grievous bodily harm on prison officer Richard Thompson after relations between Muslim inmates and guards “became strained” in the days following the murder of Fusilier Rigby in London.

Judge Michael Topolski QC sentenced Khan to six years for threats to kill and three years for GBH, to run concurrently at the end of his life sentence with a minimum of 20 years.

Awale was also sentenced to six years for threats to kill, to be served at the end of his life sentence, which carries a minimum term of 38 years.

Passing sentence, the judge said: “This was a premeditated, well-planned and carefully-orchestrated attack on a single and previously identified prison officer, who was, as such, performing a public duty and upon whom it has had a significant impact.

“The events as a whole formed part of a joint enterprise involving force and weapons, committed by men with convictions for murder.

“Both of you carried weapons to the cleaning office.

“Given the context, the level of threats uttered and repeated were truly appalling, causing great anguish, not just to prison officer Thompson, but also his colleagues who were convinced he was going to die in horrific circumstances.”

Judge Topolski told Khan that the incident had been his plan and he had recruited the others.

The men were cleared by the jury of charges of false imprisonment during the four-and-a-half-hour stand-off.

Khan was also found not guilty of assault occasioning actual bodily harm against another officer.

Their trial earlier this year heard allegations that the defendants called for the release of Abu Qatada and Roshonara Choudhry, a student who attempted to stab MP Stephen Timms to death in 2010.

They were also accused of demanding to be flown to Afghanistan.

Awale had taken knives from a cleaning office cupboard and rubbed them together giving the impression he was “preparing to carve a Sunday joint”, the judge said.

He told Mr Thompson: “Stop struggling – I’ve killed two people, I will kill you, I will kill you.”

The officer said he had “every belief” he would be killed if he did not do as ordered because of the “intensity and seriousness” Awale had displayed.

Awale at one point asked Khan, “can I give him one in a non-vital area?” and later said, “I thought his head would have come off by now.”

Khan told Mr Thompson that he had more reason to be fearful because he was believed to be ex-military.

When he denied having been in the military, Khan told the officer: “Well, somebody has to make a sacrifice.”

Paul Hynes QC, defending Khan, said his client had hit Mr Thompson “harder than he meant to and harder than was necessary, by his own admission”.

But he claimed that, based on the jury’s decision to acquit him of the charge of false imprisonment, it could be said that his client’s actions amounted to a case of “excessive self-defence”.