What will police do after they arrive at the scene of an arrest?

Upon arriving at the scene of an arrest, the police will investigate and collect evidence as part of their procedure. This is crucial for ensuring that a thorough and accurate account of events is established, which aids any subsequent legal processes. Police may gather physical evidence, take photographs, and document the scene to support their case.

The investigation also includes interviewing witnesses and the suspect to gain a comprehensive understanding of the situation. This step is vital for determining whether the arrest was justified and for the prosecution's building of a case against the suspect, as well as to safeguard the rights of all parties involved.

The other options do not align with standard police procedures. Leaving immediately would neglect the responsibilities of law enforcement to document and understand the circumstances surrounding an arrest. Sending the suspect home would undermine the legal process since an arrest implies that there are legal grounds for detainment. Focusing solely on witness interrogation, while important, is an incomplete view of the investigation process, which necessitates a broader examination of the situation and evidence.