'I do like the thrill of the chase'

Detective Sergeant Callum Sutherland, 48, is a crime-scene manager for the Metropolitan Police, based in south London

How do you manage a crime scene?

For us to be busy, the sad part is that it usually means someone has died. I work for the Serious Crime Directorate, which deals with murder, serial offences such as rape, and suspicious death scenes. I look after the forensic side of things from start to finish.

The first thing I do at a murder scene is ensure that the police cordons are in place. Everything is photographed or videotaped. Then I discuss the forensic strategy with the senior investigator. You have to decide how to assess the evidence, based on the facts as you know them.

For example, you need to know if anything has been moved, or touched. If the weather is bad, you may need to work fast to preserve evidence. If there's a lot of blood, I would call in a forensic biologist specialising in blood-pattern analysis. It's a bit like building blocks.

Does the job stop there?

No. Once I have retrieved the forensic exhibits, I sit down with the senior investigator and exhibits officer and discuss what we've got that may help us to find out who the suspect is. For example, if someone has used sticky tape to tie someone up, there could be fingerprints, fibres, or DNA on it.

Once we have submitted our evidence, I meet the lead scientist on the case to discuss anything we haven't thought of. I may not know all the answers, but I usually know someone who does, whether it's a firearms expert, an archaeologist, or a palynologist (a pollen and spore expert).

What is the toughest thing about the job?

One of the more unpleasant things to deal with is the murder of children, particularly when they are of a similar age to your own. Mass disasters, such as the Paddington rail crash and terrorism, are very hard.

You already know how people have died, so it's a case of identifying the deceased and trying to put families' minds at rest. You think, I'm the lucky one, I'm still here. Those poor people were just in the wrong place at the wrong time.

What's rewarding about your line of work?

I like trying to work out what has happened - I suppose you could call it the thrill of the chase. It's putting the pieces of a jigsaw puzzle together. If you get a conviction on the basis of evidence or an idea you've suggested - or you've tried a new approach and it has worked - that's rewarding. And there's variety. You could do a week of night shifts and nothing happens, then suddenly get a phone call. You never know what the next case is going to be.

What skills are essential in managing a crime scene?

An ability to think laterally, and be objective. Finding someone's DNA at a scene doesn't mean they've committed the crime. You've also got to ask yourself what evidence is pointing away from a suspect. It helps to understand where the scientists and detectives working with you on the case are coming from. If you don't communicate, you could end up with an innocent person being convicted.

What advice would you give someone who wanted to do your job?

In my day, you didn't get a look in until you had 20 years' experience as a serious-crime detective. Now there are universities that do forensic-science degrees, which give a good grounding in forensics. Check that the Forensic Science Society accredits any course you're considering. Otherwise, a good degree in chemistry or biology helps.

What's the career path and salary like?

Nowadays, becoming a crime-scene manager takes 10-12 years, minimum. You might start as an assistant forensic practitioner for at least three years, then become a forensic practitioner for at least a year, then become a senior forensic practitioner. At every stage, you sit an interview. The starting salaries are £15,000-£18,000, although senior crime-scene investigators can earn more than £35,000 per annum.

For more information on becoming a crime-scene investigator, consult www.centrex.police.uk

DS Sutherland appears in 'Get Dead (You've Got to Laugh)' by Jamie Oliver, (Friday Books, £9.99), which is out tomorrow