I think it’s an compound sentence :) sorry If I’m wrong!
the undercover agent still investigating the case is a run-on sentence
If you don’t give the passage then no one can help you
(I’m not just trying to get points reply to this with the passage and ill help)
Subsequent is a time later or more recent than.
Answer: Clear
Explanation: prepositions are limited in number, they are important especially in a sentence because they act as vital markers to the structure of a sentence making the sentence clear.