People have a funny idea about police officers. For one thing they seem to think we’re perfectly happy to rush in to whatever emergency there is without any thought for our own safety. And it’s true we’re like fire fighters and soldiers, we tend to go in the wrong direction vis-à-vis trouble, but it doesn’t mean you don’t think. One thing we think about is the electrified third rail and just how easy it is to kill yourself on it. The safety briefing on the joys of electrification were delivered to me and the waiting forensics types by a cheerful-looking BTP sergeant called Jaget Kumar. He was that rare breed, a BTP officer who’d done the five-week course on track safety that allows you to traipse around the heavy engineering even when the tracks are live.

‘Not that you want to do that,’ said Kumar. ‘The principal safety tip when dealing with live rails is not to get on the track in the first place.’

I went in behind Kumar while the rest of the forensics team hung back. They might not be sure what it is I really do but they understand the principle of not contaminating the crime scene. Besides, that way they could wait and see whether Kumar and I were electrocuted or not before putting themselves in danger.

Kumar waited until we were safely out of earshot before asking whether I really was from the Ghostbusters.

‘What?’ I asked.

‘ECD 9,’ said Kumar. ‘Things that go bump in the night.’

‘Sort of,’ I said.

‘Is it true you investigate,’ Kumar paused and fished around for an acceptable term, ‘unusual phenomena?’

‘We don’t do UFOs and alien abductions,’ I said, because that’s usually the second question.

‘Who does the alien stuff?’ asked Kumar. I glanced at him and saw he was taking the piss.

‘Can we keep our mind on the job?’ I said.

The blood trail was easy to follow. ‘He kept to the side,’ said Kumar. ‘Away from the centre rail.’ He shone his torch on a clear boot print in the ballast. ‘He was staying off the sleepers, which makes me think that he had some variety of safety training.’

‘Why’s that?’ I asked.

‘If you have to walk the tracks with the juice on then you stay off the sleepers. They’re slippery. You slip, you fall, you put your hands out and zap.’

‘Zap,’ I said. ‘That’s the technical term for it, is it? What do you call someone who’s been zapped?’

‘Mr Crispy,’ said Kumar.

‘That’s the best you guys can come up with?’

Kumar shrugged. ‘It’s not like it’s a major priority.’