Two teenagers have been jailed for stabbing a schoolboy to death after he was to stand as a witness in a court case.

Christopher Knox was killed by John Paul McCowan and his friend David Paton in Greenock last June.

The 17-year-old schoolboy was stabbed through the heart in the attack in the town’s Kylemore Terrace, while the trial had heard that Mr Knox was a witness in an assault case against Paton.

Previously, the court heard that Paton believed that Mr Knox was a "grass" and was trying to intimidate him to prevent him giving evidence in court.

McCowan, 17, was found guilty of murder and Paton, also 17, was convicted of culpable homicide last month.

At the High Court in Glasgow on Thursday, McCowan was sentenced to 17 years and nine months for murder and Paton was imprisoned for 13 and a half years.

Co-accused Sean O'Neill, 19, was sentenced to four years' detention after pleading guilty to assaulting Mr Knox before the teenager was stabbed to death.

David Rice, 18, and Adam Johnston, 17, admitted reduced charges of assault during the trial earlier this year and Judge Rae deferred sentence on both of them for a period of eight months to be of good behaviour.

Judge Rae described the killing as an "appalling" attack on the teenager two days after his 17th birthday.

IN DETAIL

• Judge Rae's sentencing statement in full