The short answer is – save lives and don’t worry about the crime scene! Preservation of life should always be the priority of first responders at the scene of a terrorist incident. The senior investigator should recognise this too. It is inevitable that the life saving process means that first responders will leave traces of their presence at the scene – footprints, DNA, fibres and so on – and take some forensic evidence away from the scene when they leave. This is, after all, what Locard’s Principle is about: every contact leaves a trace. Having said this, damage to vital forensic evidence can be minimised by creating a common approach path, so that all responders come and go using the same route. It’s vital too that access to the crime scene is kept to a minimum and that a record is kept of every person entering the scene and the reason for their presence there – a crime scene log. Once the life saving is over, the scene should then be preserved for the crime scene investigators to start the process of collecting forensic samples and working out what was left by the criminals and what was left by first responders. They will refer to the crime scene log to help them eliminate samples left accidentally by those involved in the all important life saving process.