The television drama Vigil has sparked curiosity about the workings of the Navy and submarines.
It tells the fictitious story of a murder on a vessel carrying nuclear missiles, following a police officer played by Suranne Jones as she boards the boat to investigate.
The first episode sees her character, Detective Chief Inspector Amy Silva of the “Scottish Police Service”, flown out to the submarine by helicopter as it continues its patrol at sea.
She is tasked with carrying out interviews and forensic investigations alone, while her efforts are frustrated by suspicious crew members with mysterious motives.
A naval source told The Independent that if a murder took place on a submarine in real-life, the investigation would happen rather differently.
In the scenario shown in Vigil, where the boat is already out on patrol as part of Britain’s “continuous at sea deterrent “, an initial investigation would be carried out by those on board.
A small group of officers on each submarine are trained to deal with serious crimes on top of their routine duties, and a dedicated compartment contains devices to take photos and other evidence.
If someone was killed on board, the area would be treated as a crime scene and detailed photos would be taken in order for a reconstruction to be created if necessary, the source said.
All the officers involved would normally be on other duties because, the source said, there cannot be “one person permanently doing nothing in case someone dies”.
Initial statements would be taken from the crew, and those documents and all other evidence would be handed over to a civilian police force on the submarine’s return to base.
The naval source said that in an extreme circumstance, a commander could choose to cut a patrol short, but that it was more likely in the case of a Trident submarine that the journey would be finished as planned.
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“At that point, the information would be handed to a regional police force that would do the investigation with whatever support the Navy provides for them,” he added.
“The Navy would be falling over backwards to find out what went wrong.”
The response on board would be led by a “senior rating”, or coxswain, and then a commanding officer would make a decision on where to put the body.
In Vigil, the victim Craig Burke, played by Martin Compston, is stored in a torpedo tube because – as another character explains – it would be cooled by the sea water.
The naval source said that in reality, a body would most likely be put in the submarine’s main fridge, after any food stocks were taken out.
He said a torpedo tube would hypothetically work for a short time, but that the Mediterranean Sea would certainly be “too warm” to preserve a body for later examination.
Asked whether there were any circumstances where a civilian police officer would be taken out to a submarine on patrol, the source said local police could board a boat that was moored or at its home base or on exercises.
He thought it unlikely during an active patrol given safety and training issues, as well as the fact that the amount of food and oxygen needed is carefully calculated according to crew numbers.
Vigil airs on Sundays at 9pm on BBC One