Bloodstain patterns tell stories. But there is always more than one story, and you need to know how to read the pattern to weigh up the most likely one. “That’s how they found him,” said Allan, pushing the book of scene photos towards me, first thing on a Monday morning. I looked at the image of a naked man covered in blood. He was lying on the floor of one of those long narrow bathrooms that are typical of an Edinburgh tenement. “That’s the blood I wasn’t sure about,” he said, pointing to some blood on the floor. Allan had been called to the scene when the murder was discovered on the Saturday night.
Any of my other colleagues who had felt out of their depth at a scene would have called for advice. Allan was educated and intelligent; but he was a chancer. Buoyed up by the buzz of a murder scene and all its accompanying drama, he dealt with it on his own. Now he had been stewing all weekend. I asked him what he had told the police but didn’t get a clear answer. This was another bad sign. Poor advice damages delicate relationships between experts and investigators. And it might be me who ended up giving evidence on the case in court.
We went back out to look at the scene together.
The naked victim, with multiple stab wounds, had ran from his attacker into the bathroom. From the bloodstains on the floor I could see he had been standing with his back against the bathroom door, pressing it closed – literally – for dear life. He bled to death standing there. I could see what had caused Allan’s confusion: the blood running down the man’s body from his wounds had dripped from him into pools at his feet. When blood drips into liquid blood like this, it creates a pattern that can look like the pattern from an impact where someone has been punched, kicked or struck with a weapon.
But if he was in the bathroom on his own, how could he be attacked in there? This was the question causing Allan’s anxiety. It wasn’t a question I needed to consider, because anyone who knew what they were doing would have recognised this pattern for what it was; blood dripping into blood.
Once I sorted this out the investigators pressed me for more information; where did the attack begin, and what were the sequence of events? There wasn’t much blood anywhere else in the small one-bedroom flat. Unlike blunt trauma – striking someone with something heavy – stabbing doesn’t tend to produce distinct patterns in blood. Sometimes there is no blood at all at the scene, because the bleeding is internal.
I looked at the bed in the bedroom next door to the bathroom. There was some smeared blood on one of the pillows and the lower bed-sheet. The investigators told me the weapon was a large knife with a long blade, something they had learned from the post-mortem examination.
I looked at the ceiling: there was no blood. I stood at one side of the bed. If he was attacked from this position, blood might have been thrown from the knife. Blood thrown from a weapon like this forms an easily recognisable pattern called ‘cast off’, but you don’t see it very often. I couldn’t see any blood on the walls nearby either. I went to the other side of the bed. This was nearer the window and the curtains were closed. Had the curtains had been closed when the police arrived? Yes, apparently.
I examined the curtains and found there a small angled cut, a few millimetres long, and about a metre from the floor. I followed the angle of the cut towards the ceiling and found three tiny bloodstains that were in line with it. The three stains were typical of ‘cast off’ blood, and these droplets had been thrown from the knife blade as it was being drawn back by the killer. The dead person had been attacked in bed and this is probably where it all started. I asked the scene examiners to pack the curtain up so it could be examined in the lab. The blood was probably from the victim: but there is always a chance that the attacker was cut, especially if the weapon had a long blade. There were no other leads, so they wanted this done urgently.
I examined the curtains as soon as they arrived at the lab. I made a note of the packaging and the label. The label had Saturday’s date on it. This conveniently obscured the fact that the blood on the curtains hadn’t been spotted until I went to the scene on the Monday.
I picked up the phone and called the crime scene manager, an experienced Detective Inspector.
“You don’t understand,” he said…I had heard it all before. Someone had cocked-up on the dates, and this would avoid a bollocking. I interrupted the Detective Inspector: “The last time this happened in one of my cases the cop ended up in the dock with me in the witness box giving evidence against him.” There were no winners. “My scene note records the curtains as being in the flat on the Monday and my court report would say the same,” I said, and put the phone down.
Later that afternoon I phoned the investigating officer. “The blood matches the victim,” I said. “He was attacked in bed and that’s probably where it started. Yes, there are other possibilities,” I said in response to his questions, “but this one is the best one.”