Controlled demolition would have required unimpeded access to the WTC, access to explosives, avoiding detection, and the expertise to orchestrate the deadly destruction from a nearby secure location. Such access before 9/11 likely depended on complicity by one or more WTC security companies. These companies focus on "access control" and as security specialist Wayne Black says, "When you have a security contract, you know the inner workings of everything." Stratesec, a now-defunct company that had security contracts at the World Trade Center and Dulles International Airport, should be investigated, among others, because of the strange coincidence that President Bush’s brother, Marvin P. Bush, and his cousin, Wirt D. Walker III, were principals in the company, with Walker acting as CEO from 1999 until January 2002 and Marvin reportedly in New York on 9/11. At least one report claims that a "power down" condition prevailed on September 8–9 (pdf, p. 45) at WTC to complete a "cabling upgrade," presenting an opportunity to plant explosives with low risk of detection.