<p><br /> Cumbrian gunman Derrick Bird was embroiled in a major tax investigation and was facing serious financial difficulties, a friend has said.<br /> </p><p><br /> Bird's fear that he may go to prison may have been the spark that led him to go on a killing spree in Cumbria, shooting dead 12 people before taking his own life in woodland, according to the latest theory.<br /> </p><p><br /> The taxi driver had told friends the Inland Revenue was investigating him for an undeclared £60,000 in his bank account.<br /> </p><p><br /> Friend and fellow taxi driver Mark Cooper said Bird was scared of prison, adding: "He didn't want to go."<br /> </p><p><br /> The claims follows reports that Bird may have argued with colleagues and family members before going on the rampage.<br /> </p><p><br /> Police have been removing his personal effects from his house as they continue to search for a motive.<br /> </p>
