The 5th amendment.
Further explanation:
If you have seen those crime shows, usually the defendant is asked if they want to plead the fifth, which means they do not have to testify in court (no self incrimination).
Answer:
Yes, law enforcement can use the recording in court because it is a direct personal threat.
Explanation:
Pat is threatening Terry with violence and possible murder, which is impiled when Pat said "No one will ever find your body". This can be used in court to support Terry's case that Pat has or could become violent and hurt Terry at some point.
