"Who's on first?" was a comedy routine performed by Abbott and Costello hundreds of times during their career. A similar routine is played out every day by police departments across the world, but this is simply not a comedy. Who is in charge at a crime scene? Who determines when and how to leave it?
Politics aside, the governor, mayor, or police commissioner may try their best to get in front of the cameras at a high-profile crime scene, but they are not in charge of it. In fact, the investigator or investigative supervisor who is in charge of the case should make very clear arrangements to keep these VIPs and the press at a command post that is far enough away so that the actual scene cannot be observed or inadvertently altered.
As a general rule there can be only one person in charge of the crime scene. Should it be the detective that is in charge of the investigation? How about the detective supervisor or commander? Does it really matter? Yes, and in my opinion the person who is in charge of investigation, the one who will be responsible for the follow through to the ultimate closing of the case and possible prosecution, should rule the crime scene.
There are certainly exceptions to rules. For example, if there is structural damage to a building as the result of an explosion or fire, the detective's control will be trumped by the immediate danger that may be obvious to a fire chief or building department engineer.
So now it's been settled. Who's in charge? You are! You've set up a distant command post including telephones, ensured that anyone who is injured has been treated and removed, created a perimeter to safeguard the scene, segregated witnesses, photographed, sketched, taken video, had the crime scene techs finish processing, secured and preserved evidence, etc. What more is there to do? Leave?
How you leave the crime scene will depend on the type of crime, and its location. For example, if you are investigating the theft of precious art from a museum you will need to secure the premises until someone of authority arrives so as to prevent further thefts. You should document the time, identity and authority of the person to whom you release the scene.
If you are at the scene of a building explosion you will need to seek out someone of competent authority to determine if the building is safe to return to, or if it should be closed pending review by the local building department.
One thing in common at most every crime scene is that there will be someone who will ask the question, "What happens next?"
As the investigator in charge you must be able to explain to victims or family members what will happen next, and what if anything they will need to do. At burglaries you may tell the victim(s) that you will be submitting any latent prints as well as the comparison prints of the victims or anyone else with legitimate access to the crime lab, and that you will be visiting local pawn shops to locate their property. You may also suggest that the victims visit these pawn shops as well, and to contact you directly if they recognize their property. You may tell them that you will be reviewing and continually monitoring other crimes in the area to determine if the same M.O. was/is used. Remind them that they should prepare an exact list of stolen articles for you, and to forward the list to their insurance company and include the loss on the federal income tax Return.
At robbery scenes, sex crime scenes, or any other scene where the victims or witnesses were able to view the perpetrator(s), in addition to telling them about latent prints and M.O.s, you will also want to have them look at photographs at your identification unit or your office. You should also let them know that you may bring photo arrays to them in the future. They should be told what to do in the event that they see the perpetrator(s) again, i.e.; call 911, write down plate numbers, try to avoid confrontation prior to police arrival, observe clothing, observe activities (food shopping, banking, etc.) direction of travel, associates, etc.