Let's say a police officer searches a property without a warrant, and discovers a couple of people imprisoned there.
Would their testimony against the owner later be inadmissible as it's a result of the illegal search?
First, if the police officer had reasonable cause to believe that a crime was in progress then the search would not be illegal in the first place. However, let's assume the search was illegal.
The evidence of the police officer as to the imprisonment would be excluded. However, the evidence of the victims is independent of that illegal search and their testimony would be admissible. Further, that testimony would allow independent discovery and admissibility of any physical evidence in the property.
However, if the victims were dead, then there would be no independent discovery and none of the evidence would be admissible.