The gunman who carried out the Cumbria massacre was facing a major tax investigation into £60,000 of undeclared savings and was terrified he could go to prison.
Friends and colleagues have revealed that Derrick Bird was embroiled in an investigation into his bank account and was facing serious financial difficulties.
Detectives are working on the theory that Bird harboured “grudges” against several of his victims following disputes over money.
Several of those killed in the early stages of his killing spree had clashed with Bird over the past few weeks including his twin brother David and the family solicitor Kevin Commons.
However, the taxi driver's rampage across Cumbria, during which he killed 12 people, is thought to have also involved the killings of several bystanders unknown to Bird.
It can be disclosed that Bird and his twin brother had had a rocky relationship since their childhood. Family members of David Bird said that his only downfall “was to try and help” his twin.
However, the dispute is alleged to have escalated recently when his brother David reported Derrick to the authorities for avoiding tax.
A friend of the killer told this newspaper yesterday that Bird had about £60,000 in undeclared and untaxed earnings in a bank account which the tax authorities had since discovered.
Bird was said to have been concerned that he would be imprisoned for the alleged tax evasion.
Mark Cooper said: “He had this £60,000 in his bank and the tax man had found out. He was terrified he was going to go to prison. It had been going on for six months but he only told me a fortnight ago. I had never seen him bothered about anything before.”
Last week Bird is understood to have been given details of his mother's will — which was drawn up by his twin brother and Mr Commons, a local solicitor.
There was speculation that this information is thought to have been the final catalyst for Wednesday's tragic events, which ended when Bird took his own life.
Mr Commons, one of the area's best-known lawyers, was the first man to be murdered on Wednesday morning on the driveway of his Cumbrian home.
Bird then drove to his twin brother's house in a nearby village and executed him while he was still in bed.
The taxi driver is also thought to have fallen out with several of his colleagues whom he later shot — after they were accused of failing to follow the rules when waiting for paying passengers.
The drivers were also reported to have clashed during a recent shared holiday in Thailand after Bird paid a large amount of money to a local woman.
At least two of the victims were also relatively well-known employees at the Sellafield nuclear power plant — where Bird worked until he was sacked and prosecuted for theft in 1990.
One of them was a retired security worker.
Last night the detective leading the investigation disclosed that the killings were thought to be a mix of people that Bird had targeted and random murders.
Det Chief Supt Ian Goulding said: “A key part of the ‘why' in this investigation is whether these victims were chosen because of a motive, because of a grudge, or were they simply random killings? Our initial assessment is a combination of both of these.”
Mr Goulding, who is leading a team of 100 detectives investigating the shocking killings, confirmed that lines of inquiry included Bird's “financial and domestic matters”.
The detective suggested that Bird had “a number” of weapons lawfully in his possession — implying more than the two recovered at the scene.
He said that he had no record of mental health problems, was using no medication, and that he had previous convictions, the last of which was for theft in 1990.
He had never been jailed for an offence, police said.
However, police are investigating whether Bird had a history of self-harm after they found extensive evidence of scarring to the killer's body which appears to go back several years.