The attenuation doctrine is one of three limitations on the fruit of the poisonous tree doctrine. Once it is determined that a Fourth Amendment violation was the cause of obtaining the evidence, the evidence may nevertheless be admissible if the causal connection between the illegality and acquisition of the evidence is sufficiently remote or attenuated so as to purge the original illegality of its taint. State v. Grayson, 336 S.W.3d 138, 147 (Mo. banc 2011). Three factors are examined when determining whether evidence retains the taint of a prior illegal seizure:
1. The temporal proximity of the illegality
2. The presence of intervening circumstances
3. The purpose and flagrancy of the official misconduct
Id. at 147.
In Grayson, an officer received an uncorroborated anonymous tip of a possible drunken driver with the name of Reed who was operating a red Ford pickup truck. Id. at 141. The officer knew Mr. Reed and knew that he had an outstanding parole warrant. Id. The officer did not find a red Ford pickup, but he did observe a red Mazda pickup approximately one-half mile away from the reported location. Id. The officer also recognized the driver of the Mazda truck as being one Matthew Grayson, a person he knew to have had some prior arrests. Id. On this basis, the officer initiated a traffic stop of Mr. Grayson even though he was not the person named in the tip, he was not operating a Ford truck, and at the time of the stop the officer knew of no specific facts that would justify a traffic stop. Id.
The officer informed Mr. Grayson that he was conducting an “investigatory stop,” asked him for his license, and checked for outstanding warrants. Id. at 141–42. During the warrant...
