Iraq Survey Group (ISG), headed by American David Kay, was tasked with searching for weapons of mass destruction. The survey ultimately concluded that Iraqi production of weapons of mass destruction ceased and all major stockpiles were destroyed in 1991 when economic sanctions were imposed, but that the expertise to restart production once sanctions were lifted was preserved. The group also concluded that Iraq continued developing long-range missiles proscribed by the UN until just before the 2003 invasion. In an interim report on 3 October 2003, Kay reported that the group had "not yet found stocks of weapons", but had discovered "dozens of weapons of mass destruction-related program activities" including clandestine laboratories "suitable for continuing CBW [chemical and biological warfare] research", a prison laboratory complex "possibly used in human testing of BW agents", a vial of live C. botulinum Okra B bacteria kept in one scientist's home, small parts and twelve-year-old documents "that would have been useful in resuming uranium enrichment", partially-declared UAVs and undeclared fuel for Scud missiles with ranges beyond the 150 km UN limits, "[p]lans and advanced design work for new long-range missiles with ranges up to at least 1000 km", attempts to acquire long-range missile technology from North Korea, and document destruction in headquarters buildings in Baghdad. None of the weapons of mass destruction programs involved active production; they instead appeared to be targeted at retaining the expertise needed to resume work once sanctions were dropped. Iraqi personnel involved with much of this work indicated they had orders to conceal it from UN weapons inspectors. After Charles Duelfer took over from Kay in January 2004, Kay said at a Senate hearing that "we were almost all wrong" about Iraq having stockpiles of weapons of mass destruction, but that the other ISG findings made Iraq potentially "more dangerous" than was thought before the war. In an interview, Kay said that "a lot" of the former Iraqi government's weapons of mass destruction program had been moved to Syria shortly before the 2003 invasion, albeit not including large stockpiles of weapons. On 30 September 2004, the ISG, under Charles Duelfer, issued a comprehensive report. The report stated that "Iraq's weapons of mass destruction capability ... was essentially destroyed in 1991" and that Saddam Hussein subsequently focused on ending the sanctions and "preserving the capability to reconstitute his weapons of mass destruction (WMD) when sanctions were lifted". No evidence was found