A knife-wielding former paratrooper who repeatedly stabbed a man in an ambush has been jailed.
Richard Grant, 46, used his military training to spy on Alex Pierce before he attacked him with a commando knife.
Mr Pierce had previously been in a relationship Grant's partner and Grant wrongly believed he had abused her.
Grant was sentenced to 12 and a half years at Exeter Crown Court for wounding with intent and possessing an offensive weapon in public.
He told police he had fitted a tracking device to Mr Pierce's car and was spying on him because they had "let a monster out on the street".
Grant ambushed Mr Pierce as he parked his car one night in January in Leighton Terrace, Exeter.
Grant had disguised himself in black.
Mr Justice Dingemans said: "Grant was exercised by the sexual relationship that had happened in the past."
The judge said Grant would check the tracker "seven or eight times a day" to see where Mr Pierce was. He said Grant had become "obsessed" with him.
Grant claimed someone else carried out the stabbing. A jury cleared him of attempted murder, but convicted him of wounding with intent.
He admitted possessing an offensive weapon in public and was jailed for two years concurrent to the twelve and half years.
The court heard Grant served in 2 Para for 10 years and claimed he was suffering from post-traumatic stress disorder as a result of eight tours of Northern Ireland during the Troubles.