Once a crime is reported, a police officer will be sent to the scene, alongside any other emergency services should they be required, based on the requirements of the victim, for example if they require an medical attention, and ambulance will be sent to the scene.
The initial response is crucial to any investigation as if someone is in danger, someone's life could potentially be saved, by sending an ambulance to the scene, to that they can be given medical attention. It is also crucial as evidence can degrade over time, therefore making it crucial that the police and crime scene investigators are at the scene in as little time as possible.
It is also during the initial response that the handlers and officers can gain any initial information from the scene from the person calling the emergency services. The information given in these calls is analysed, leading the call to be placed on a priority list- meaning that someone who has been stabbed will receive attention before someone with a cat stuck in a tree.
The OJ Simpson Case
In the case of the OJ Simpson investigation: on the evening of the 13th of June 1994, Nicole Brown Simpson's neighbours, Bettina Rasmussen and her husband found her body alongside the body of Ron Goldman... both slaughtered outside of her home at Bundy. The neighbours found the bodies due to the excessive barking from a dog which was covered in blood.
They then dialled 911, in order to inform the police of the wreckage that lay before them. The police responded to the call by sending both police and paramedics to the scene. Police Officer Robert Risk was the first attending officer.