Answer:
Presence of the perpetrator .
Explanation:
Okay, let us first fill in the gap from the question:
''In general, officers are permitted to conduct a protective search or sweep of the premises when they have reasonable grounds to believe that a person within the premises is in immediate need of assistance or THERE IS PRESENCE OF THE PERPETRATOR''.
Yes!, the above statement is correct. Officers of the law are given this right which is provided for them in the Fourth Amendment to the United States of America Constitutions. In order to conduct "a protective search or sweep of the premises" the officers need a search warrant which is provided to them by the court. And, there are also some cases/times when the officers do not need a search warrant for conducting their searches.
