Michael was killed because he was living proof of the "Arab-specific" nature of the tag used in the whole experiment that Cooper was running. So, as part of the clean up process, he had to be disappeared, just like Cooper himself, and all the other bodies of the refugees who had died from the jab. Yasim and Steven were both left alive, I think, because without Michael -- or any of the other test subjects -- they had no physical evidence for any of their allegations against the government. So they both sound like paranoid fringe loonies, or criminal types, etc. If they are left alive they do more to benefit the government, by making it possible to hold up critics of the TIA or Tagme programs to ridicule, etc.   See 3 other replies

The US also has ADVISE (Analysis, Disseminatin, Visualization, ingight, and Semantic Enhancement) to pull together all info, including media, to link people and suspicious activities. This eventually transitioned into "fusion centers", which pull together commerical, banking, education, transportation, hotels, real estate with on-line activities, and local and state police and intellgence agencies. There is also Pathfinder, which the Dept of Defense uses to compare government and commercial databases.There is also TALON (Threat and Local Observation Notice), to spy and report on Iraq-War protestors, making the data available to government agencies, national and local.This doesn't include all the phone logs, cell phone bills, utility bills (useful for finding households with people who come and go).REVEAL combines government databases with private companies.   See 2 other replies