A chilling tape of the row which ultimately prompted Raoul Moat to go on his "murderous" rampage was played to an inquest jury today.
In the recording, Moat could be heard reacting furiously to his girlfriend Samantha Stobbart telling him their relationship was over.
Moat, who went on to shoot Miss Stobbart and murder her new boyfriend, complains that "everybody is getting on my case" and that he is getting "picked on".
The call, made while Moat was in Durham Prison, then ends abruptly.
Superintendent Jim Napier, outlining the investigation into Moat at the start of the inquest into his death, said: "It is clear from the evidence that Moat's break-up with Samantha Stobbart was the catalyst for his murderous acts."
Moat, 37, died during a six-hour stand-off with police marksmen after a rampage of violence which left one man dead and two people maimed.
The former bouncer shot himself in the head and was fired at twice during the stand-off by officers armed with new XREP shotgun Tasers.
The jury will decide whether the Taser rounds fired from experimental weapons may have caused the former nightclub doorman's death during the tense stand-off in Rothbury, Northumberland in July last year.
The jury panel of 11 sworn in at Newcastle Crown Court today were told by Coroner David Mitford that an inquest was needed because "Mr Moat met his death when he was effectively detained".
Barristers for the Moat family, the Chief Constable of Northumbria Police, West Yorkshire Police officers and Pro-Tec Limited, the firm that supplied Taser weapons, were in court, Mr Mitford said.
He added: "It will not have escaped your attention that there were some weapons called Tasers used on the night in question.
"Those Tasers were supplied to Northumbria Police by a firm called Pro-Tec Limited."
He asked the jurors to try "the impossible" and forget what they have already heard about the Moat case.
"There have been lots of theories and conclusions drawn, some of which may have been accurate, some of which may not."
The inquest will focus on the events in Rothbury on July 9 and 10, he said.
There will be questions about weapons used, how police managed the incident, how officers dealt with the deceased and how he acted, the jury was told.
But it will first hear why so many officers were involved in the "manhunt", the coroner said.