FBI Tested Brushes, Debris From Holmes' Apartment FBI chemists say they were asked to test paintbrushes and small samples of debris found in the apartment of Colorado theater shooting defendant James Holmes. The chemists testified Tuesday in a pretrial hearing to determine whether their testimony should be allowed at Holmes' trial. Holmes pleaded not guilty by reason of insanity to charges of killing 12 people and injuring 70 in the July 2012 attack. At hearings this month, prosecutors and defense lawyers are arguing over evidence that could be used to weaken his insanity claim. It's not clear how the chemists' testimony might fit into the larger sanity debate, or whether it might play another role. The chemists say they found salt, a form of plastic and a variety of chemicals in their tests.