In 1991, the Calvi family commissioned the New York-based investigation company Kroll Associates to investigate the circumstances of Calvi's death. The case was assigned to Jeff Katz, who was a senior case manager for the company in London. As part of his two-year investigation, Katz instructed former Home Office forensic scientists to undertake forensic tests. They found that Calvi could not have hanged himself from the scaffolding because the lack of paint and rust on his shoes proved that he had not walked on the scaffolding. In October 1992, the forensic report was submitted to the Home Secretary and the City of London Police, who dismissed it at the time.