What is the burden of proving by a preponderance of the evidence?

Although the government has the burden of proving by a preponderance of the evidence, United States v. Schipani, 414 F.2d 1262 (2d Cir. 1969), that the evidence has not been tainted either indirectly or directly, an inquiry must first be made as to the cause of the investigation. If the investigation was in fact instigated by information that was discovered independently of the illegal intrusion and if the illegally obtained information would not have been, in and of itself, sufficient in the normal case to trigger this type of investigation, then the investigation has not been tainted and no indirect, derivative taint attaches to any of the evidence produced by the investigation. Second, the law focuses attention on the investigative findings themselves. If the evidence produced by the investigation was simply the normal output of that investigation, then the investigative findings have not been tainted directly.