London, June 4 (ANI): Cumbria gunman Derrick Bird's spiralling debts turned him into a mass murderer from a friendly cabbie, it has emerged.
Bird, 52, had outstanding income tax dues of more than 100,000pounds.
He wanted to settle it with a large share of his mum Mary's will when she died.
But he soon found his twin David was to be the main beneficiary.
Bird now felt he had been "stitched up" by David and his lawyer handling the will, Kevin Commons, his brother's pal.
When a taxman discovered Bird had 60,000pounds in a bank account, he was convinced David has given up on him.
Bird anger was further fuelled by grudges against his previous bosses at the Sellafield nuclear power plant and fellow Lake District taxi drivers.
David and Commons were Bird's first victims before he murdered 10 and wounded 11 others in the recent gun rampage across Cumbria.
"Derrick believed David had been sucking up to their mum to engineer a huge share of the cash. He became obsessed and finally unhinged, fearing he had been cheated by his family," the Sun quoted an insider, as saying.
Another source said: "It's all to do with income tax. David had been trying to help Derrick with his financial problems. But we think Derrick got it into his head that his brother was ripping him off."
A friend said: "It has been said there was some family problem over the will and how it would affect Derrick's tax affairs.
"The feeling was that if his mother's will was divided equally then a lot of it would be swallowed up by the taxman. I think the family thought it better Derrick's share should be as low as possible so the money didn't simply go to the Government." (ANI)