Blood Spotting Made Easier

A new camera may make finding and sampling blood spots easier for crime scene investigators. Chemist Stephen Morgan describes a thermal infrared camera developed by researchers at the University of South Carolina that can spot blood spatter not visible to the naked eye.

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IRA FLATOW, host:

Up next, a new way to spot bloodspots. Yeah, if you're a "CSI" or a "Dexter" fan, you know, "Dexter," he looks at all those blood-spatter programs, you've probably seen the crime scenes where detectives use luminal to look for their blood, or they spray the crime scene with a chemical, they turn off the lights, and they watch that eerie, blue-green glow with that little special tool they carry with them.

Well, that looks pretty good on TV. Real detectives say luminal isn't any - it's not the ideal way to find blood at a crime scene, especially when the amount of blood is small, or it's invisible, it's sprayed around, you can't really see it.

Well, now researchers at the University of South Carolina say they have invented a better way to spot that blood using a specially designed infrared camera.

Stephen Morgan is a professor of chemistry in the Department Chemistry and Biochemistry at the University of South Carolina in Columbia, South Carolina. Thanks for being with us today.

Professor STEPHEN MORGAN (Professor, Department of Chemistry and Biochemistry, University of South Carolina): Thank you, Ira, I'm delighted to be here.

FLATOW: We've only got about a minute until the break, and we'll talk more with you after the break. But how good a new breakthrough is this?

Prof. MORGAN: Well, it has the potential to be very helpful in situations where blood is hard to spot or is on dark surfaces or very dilute. And it doesn't, apparently, suffer from some of the drawbacks of luminal in terms of false-positive reactions.

FLATOW: And you just shine - what, you take an infrared picture of it? Is that how it works?

Prof. MORGAN: Well, the initial concept was to shine infrared light from a distance onto the target and see if we could detect contrast, and the image is reflected back because of its interaction with a blood stain.

And we had this idea of a laser pointer being used to indicate places where the presence of blood is suggested. And the investigator could then go with a sample, with a Q-Tip, and take a sample from that spot only, and the rest of the crime scene is untouched.

FLATOW: All right, we're going to take a break. The clock says we've got to go to a break. So we're going to come back and talk lots more with Stephen Morgan. Our number is 1-800-989-8255, if you'd like to talk about blood spatter patterns and detecting blood, as you might see it on "CSI" or "Dexter." Maybe they're going to listen to us and say: We've got to get one of those.

We'll talk about how you do that. Stay with us. We'll be right back after this break.

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FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

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FLATOW: You're listening to SCIENCE FRIDAY from NPR. I'm Ira Flatow. We're talking this hour about new technology to detect blood spatter, tiny little particles that you might not see or that escapes being detected in the normal way.

Stephen Morgan is a professor of chemistry in the Department of Chemistry and Biochemistry at the University of South Carolina in Columbia.

What made you look for a better pattern, a better way to detect the blood spatter than we have now?

Prof. MORGAN: Well, Ira, there have been many published studies in forensic and biochemistry journals that characterize blood proteins by their IR, infrared, spectra. And the infrared spectrum is not visible to the human eye, but it's an informative region for molecular structure.

The energy of IR light matches the energy levels of atomic vibrations and molecules, and by measuring wavelengths at which molecules absorb or emit radiation, one can identify them.

And blood contains proteins, which contain peptides and amino acids, which have characteristic absorption peaks in the middle of the infrared region. And so that was our original concept.

FLATOW: But do you know, when you watch television, I always see this all the time on "CSI" or whatever. And I've had other forensic scientists say to me: I wish I had that tool that they have, some magical thing that detects all these things. Do you ever think about: Gee, you know, I wish I had some miraculous new little device that they have.

Prof. MORGAN: Well, our original model for this was the "Star Trek" tricorder.

FLATOW: It was what?

Prof. MORGAN: The "Star Trek" tricorder.

FLATOW: Oh, that little wireless thing that you point at somebody and it tells you what's wrong with them?

Prof. MORGAN: Exactly.

(Soundbite of laughter)

FLATOW: So what was really wrong with luminal that we're using now?

Prof. MORGAN: Well, there's nothing really wrong with luminal, and there is no substitute for having an experienced CSI at a crime scene. It turns out that the drawbacks of luminal are that it reacts with blood by the iron in the blood being - catalyzing a reaction between luminal and hydrogen peroxide. And the reaction lasts only a few seconds.

And so you have to photograph it quick. If not, you have to re-spray the area. Also, trace blood stains may be diluted below levels required for DNA analysis. And also, blood stain patterns may be smeared or obliterated.

But a major issue for us, as an analytical chemist, I was always perturbed by the fact that it was necessary to contaminate the whole crime scene with a reactive chemical.

Now, further, it turns out that luminal is not specific, and this is the major problem. It gives false-positive reactions with many common substances that you might find in your house, including rust, certain foods such as sweet potato and horseradish, some metals and paints, furniture polish, coffee, soft drinks and cleaning agents.

FLATOW: Well, Dexter never says that when he sprays that stuff out of his bottle.

Prof. MORGAN: That's right.

FLATOW: You never see that. So have you actually created a device that you can - that it is practical and carry around with you to a crime scene?

Prof. MORGAN: Well, here's the problem. When infrared light is directed to a surface, a very large proportion of the light is simply reflected back, as if from a mirror. But a very small portion of the light enters the surface layer and interacts with the molecules present and is subsequently reflected diffusely in all directions.

It's this portion of the reflected light that contains information about the chemical nature of the surface. And our task is more difficult because depending upon their temperature, all normal objects give off black-body radiation in the infrared region.

The amount of light given off in an ordinary-sized room at room temperature is tremendous. Our eyes just don't see it. The problem of measuring a small amount of light reflected from a surface stain, well, you could make the analogy that it's like trying to spot the light from a hand-held flashlight against the backdrop of a bank of lights at a football stadium.

FLATOW: Wow. But that doesn't discourage you?

Prof. MORGAN: Well, the way we did this was we actually used an ordinary laboratory heating plate that gives out about 1,000 watts of infrared light. The infrared light is pulsed towards a target area, off and on, at a rate of about once per second by rotating a fan blade in front of the plate, and the light reflected back from the target is detected by an IR imaging camera that essentially measures the temperature rise of a sensor array. And we take 61-megapixel images per second.

There's a small gold reflector next to the target that's used for timing the data processing. And here's the problem. If you were to use the normal - the camera in a normal way and just look at all of the light reflected back from the scene and average it, we would see an infrared image with no contrast between stained areas and clean areas.

But if we process the data pixel by pixel to look at the light that is in synch - that is synchronized with the pulsing of the light source, this is known in digital processing theory as a lock-in amplifier approach, well, with this we can detect diffusely reflected light that is partially absorbed and then re-emitted with a spectral signature that depends upon the chemical nature of the surface.

And so the result is that target regions that contain a stain have different visual contrast in the image than regions that aren't stained.

FLATOW: But you don't have a device that can - you can take to the site yet and try that.

Prof. MORGAN: That's right.

FLATOW: It sounds like you need a lot of heavy computing, you need a big device. It's going to be pretty hot, 1,000 watts reflecting on somebody.

Prof. MORGAN: Actually, the data processing is done in real time. The image is displayed pretty quickly. The current instrument, indeed, is sitting on a laboratory bench, on an optical table, and it has never left that room. Further work is needed to get this instrument into a portable form and to take it to realistic crime scenes or real-world situations to test it.

FLATOW: Let me see if I can get a phone call in from Jake(ph) in Austin. Hi, Jake.

JAKE (Caller): Hi, Ira.

FLATOW: Hi there.

JAKE: I've been a cop for 40 years and a homicide investigator for the last 30 years. The changes in technology in my lifetime, that I've been doing this, are so dramatic that certainly this camera will be a boon to us.

But we're at a point now that if we have a suspect, and there's any physical evidence, our CSI technicians will get us convictions. We have a much higher conviction rate today than we ever did before, and juries love this stuff because science doesn't lie.

And the - it even impresses me. I mean, I see this every day of the week, and the ability that these CSI scientists and technicians have, we closed the books on a lot of bad guys just based on their evidence.

FLATOW: But he hasn't got a device yet. How much would you be willing to pay if he got one of these things working? Do you have a budget for that?

JAKE: I don't know that. Our CSI budget is somewhat classified within the department, but I have no doubt that - we have been at the forefront of technology for years. Our chiefs jump at stuff like that. They -anything that will increase our capabilities to convict people of crimes, they don't hesitate. If something like this came on the market, I'm sure they would jump at it.

FLATOW: All right, thanks for calling. We'll find out how soon this is going to show up. How soon do you think we might see it?

Prof. MORGAN: Well, this work was funded with a preliminary grant from the National Institute of Justice, which is the research and development arm of the Department of Justice.

The project started in 2007, and we succeeded because we had four very hardworking graduate students and a number of undergraduates that contributed to the project. Michael Myrick, my collaborator, and I worked together very hard on this project. And - but yet it's at a preliminary stage.

So we're going to be applying for more funds. We, as I said, expect to be able to take this into some more real-world situations. One thing that was interesting about costs from that commentator was that one of the objectives from the beginning was to offer a low-cost alternative.

And currently, some of the alternate light sources that are used for visualization of stains at crime scenes cost up to $15,000 or $20,000. And we expect that this device could be manufactured for less than that.

FLATOW: Well, good luck to you, and let us know when it's operational.

Prof. MORGAN: Thank you.

FLATOW: That's Stephen Morgan, he's a professor of chemistry at the Department of Chemistry and Biochemistry at the University of South Carolina in Columbia.

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