How far does the &quot;fruit of the poisonous tree&quot; doctrine go? If someone is caught using illegal evidence, and then let go because of that, can the police follow them around to see if they commit more crimes, or is that all poisoned (because if the original evidence hadn&#x27;t been obtained, they would never have found this person to follow)? Would they need to wait until the person came up in an entirely unrelated lead? Would they be able to add the information &quot;person was previously let go on technicality for crime X&quot; to a database which generates leads when cross-referencing other data (e.g. people in proximity to a crime, which might be crossed with known criminals? (I don&#x27;t know if this is actually done))