Forensics Expert Answers Crime Scene Questions From Twitter

Crime scene analyst Matthew Steiner answers the internet's burning questions about forensics and crime scenes. Why don't we use chalk outlines for dead bodies anymore? How did OJ Simpson get acquitted? How many people got away with murder before DNA evidence? How does height affect blood spatter? Matt answers all these questions and much more! Director: Justin Wolfson Director of Photography: Samuel Levine Editor: Ron Douglas Expert: Matthew Steiner Line Producer: Joseph Buscemi Associate Producer: Brandon White Production Manager: Eric Martinez Production Coordinator: Fernando Davila Camera Operator: Claudio Corredor Audio: Adam Gold Production Assistant: Ryan Coppola Post Production Supervisor: Alexa Deutsch Post Production Coordinator: Ian Bryant Supervising Editor: Doug Larsen Assistant Editor: Billy Ward Junior Editor: Paul Tael

Video Transcript

- My name is Matt Steiner.

I'm a senior crime scene analyst.

I'm here today to answer your questions from Twitter.

This is Forensics Support.

S&M79 asks, derp.

crime scene photo... why did they draw chalk around the body?

So this was an old school method that they used to use to identify where a body was within a crime scene.

Later in our investigation, after bodies removed you could see where that body was in its position.

We no longer do this because of DNA contamination and trace evidence.

So instead of chalk now, we just take detailed photographs.

We'll document that scene with laser scanner.

That laser scanner is recording millions of points per second as it's spinning and also taking imaging as it's turning.

We have that scene preserved virtually.

We can go back and look at a three model.

We could use virtual reality or augmented reality to go back and walk through that scene virtually now if we want to.

Forensicfield asks question- what are the most popular methods for searching a crime scene?

The three most common ones are a line search, a grid search and a zone search, though there are many others.

A line search, it would be a line of investigators and they would search a crime scene in one direction.

We search in one direction, we don't find anything, we could then turn that search at 90 degrees and search in another direction, and that's what's called a grid search.

Looking at it at an opposite angle at 90 degrees sometimes you'll visualize that evidence.

The last most common search is a zone search where you take a crime scene you break it down into smaller parts.

As we discover evidence, we'll go around and we'll mark this evidence and then we'll take additional photographs showing that scene with the numbers and then close up views of the evidence.

So some markers will have a scale on it to show the the size of it.

What we need to do is have a very systematic and methodical order that you pick to search these scenes.

Doing things at random, milling about is not acceptable.

JosephV977 asks, how many people got away with murder before forensic science improved and DNA?

It's a good question.

I think another good question would be, how many people were wrongfully convicted before forensic science?

Science is constantly improving and our goal is the truth and we just want our investigation to show that.

Years ago a guy goes out to his car, a bag of trash next to his door and he does what a lot of people would do, he just kicks the bag.

Unbeknownst to him, there was a pipe bomb in that bag and it detonated.

This is back in 2002 and we had no answers.

2006, I pull some of this evidence from storage and I reswabbed the wiring and the cap and the threading to the pipe bomb and send that off for analysis because in those short four years, DNA has advanced.

We identified this person inside of his car.

He had more pipe bombs and automatic weapons.

So sometimes the work that we do not only can solve crimes, but it could also save lives.

Sibajparker asks, how do forensics determine shit from blood spatter?

Are there experiments where you crack open dead bodies with different weapons under different circumstances?

First off, it's not blood splatter.

It's blood spatter.

Blood isn't always red.

It could be different colors and tones.

Blood from your arteries would be bright red, where the blood from your veins would be a darker color.

As that blood dries, it gets oxidized.

It's contaminated by the crime scene.

It could also change its color and tone.

If we have a suspect stain and we don't know what it is, oftentimes we'll do what's called a presumptive test, like we have here.

This is an OBTI test.

We'll tell you whether that sample could be blood.

You still have to sample it.

You would send it to a laboratory and they would say what it is and sometimes to whom it belongs to.

Cadavers though to your question, generally are not used for blood stain pattern analysis, but they are used at some universities and they put bodies in different circumstances.

So they'll put the body in a car, they'll put it outside in the open in a field, different environment to see how those bodies decompose over time.

Lrcf asks, how did one of the most infamous unsolved crimes committed on Valentine's Day in 1929 lead to new forensic science techniques in ballistics and a reform in gun control?

What they're referring to is the Valentine's Day Massacre in Chicago in 1929.

Seven Irish mobsters were lined up against the wall and they were shot to death.

The weapons of choice in this crime was the Thompson submachine gun or Tommy gun.

Back then, anyone could walk into a store and purchase one of these weapons.

And because of the public outcry of this case, we got our first federal gun control law which took these weapons out of the private sector's hand.

Also with this case was one of the first uses of forensic ballistic evidence.

Forensic ballistics is the study of not only firearms, but projectiles and casings related to a firearm and able to identify certain bullets or casings to a known firearm.

ScotlandYardCSI asks, how do we identify human remains?

Well it depends on the state of the remains.

Crime scene investigators work with a medical examiner's office or a coroner's office to determine whether remains are human or not human.

Remains that are in an advanced state of decomposition to the point where they're skeletal, generally wanna work with an anthropologist.

They could tell you not only whether it's human or non-human, but what part of the body it came from, possibly the age or the sex of the person by looking at different bone growth markers and then sometimes looking at the damage to these bones could determine the cause and manner of death.

CXXIV001 asks, are we sure that every fingerprint is unique?

How is it possible did you check every single one?

No, it's not possible to check every single one.

I didn't check every single one.

They look at first as a category.

They're looking at whether it's a loop, it's a whirl, it's an arch.

But then really what they're using to identify is the minutia in your fingerprints.

Anytime, if you look at your fingerprint that friction ridge split, it comes together, it starts, it stops, it ends, creates an island.

These are all points of identification that they're gonna look at.

In the hundred plus years of analyzing and comparing fingerprints, they have yet to find two fingerprints that are identical.

Govengie asks, no seriously, does anyone know how to do a druggist fold?

Sure, I could show you that now.

A druggist fold or a pharmacy fold is a way to preserve small amounts of trace evidence in paper.

The first thing you wanna do with your paper, you wanna fold it into thirds.

Fold it a third of the way in on both sides, then you wanna fold it into thirds again.

And then what you wind up, if you open this up, is you have nine equal sized boxes.

You would then collect your trace DNA and you put that trace DNA into the center square.

And then very carefully you want to close that up and make a little point on one end.

Take this point, secure it into the pocket on the other end, and that you have this little bindle now.

Then what you do is you would seal up this one end, put your signature across it, the date, and then this would be over packed into an evidence envelope.

From ChoomieTM, if our DNA could travel anywhere without us even being there how reliable is DNA and forensics after all?

DNA analysis gets more sensitive as time moves on, technology gets better, it gets more sensitive.

There's different types of crime scene contamination and there's different types of DNA transfer.

Intra crime scene contamination happens within the crime scene.

So if I touch this one object, I touch another object, I'm contaminating two different objects within the same scene.

Inter crime scene contamination is contamination between two unrelated scenes.

I'm at a crime scene, I'm standing in blood, that blood is now drying on the soles of my shoes.

I go to another unrelated crime scene.

Now that dried blood is starting to flake off into that crime scene.

That's inter crime scene contamination.

There's different types of DNA transference events that can happen.

We have primary, if I'm not wearing gloves and I touch a door handle, I'm transferring my skin cells to that door handle.

Secondary contamination would be if you and I shake hands and now I touch that door handle and I transfer your skin cells onto that door handle.

When they analyze the DNA, they could tell the difference between a major contributor and a minor contributor.

Analyst is not saying you shot that person, they're just saying that there's a presence of your DNA on that weapon.

Babiface16 asks, how in the fuck did OJ Simpson get acquitted?

Literally makes no sense.

The death of Nicole Brown Simpson and Ron Goldman, it's a roadmap of what not to do at a crime scene.

First off, there's tons of miscommunication mismanagement with the case.

Investigators first went to OJ's estate before going to the crime scene, so you have this inter crime scene contamination.

When they arrive, they're told about a bloody patent fingerprint on the gate.

So that's a fingerprint impressed in blood on the gate.

It's probably one of the strongest types of evidence you can get inside of a crime scene.

That fingerprint was never documented and never collected.

And by the time they realized it and went back to the scene, that evidence was gone, it was cleaned up.

Nicole Brown, she's outside and to cover her body from the public view they went inside and they grabbed a blanket from the home and they covered her with it.

You wanna use a clean sheet to do that.

Not something from someone's home that had already has who knows DNA on it that can be transferred to the body.

No one knew about DNA, but since then everyone knows the importance of DNA with crime scenes.

So the investigators, no fault to their own, didn't have these protocols in place and now most departments do because of this case.

I think if that crime scene happened today and if OJ really did it, maybe we'd have a different outcome today.

Vigilantedrones asks, how are drones helping with crime scene investigation and accident reconstruction?

It used to be if you wanted to get these overhead views of your crime scene, you needed a helicopter.

They're expensive, they're not gonna show up to every crime scene and there's restrictions on how close they can get to that scene.

Now we can get a drone that's inexpensive, easy to use, and put that right above the scene to get our imagery.

And there's a lot of other amazing things we could do with drones today.

We could pair this technology with laser scanning and photogrammetry to get three dimensional models of our crime scene from the air.

We could put an infrared camera on our drone to search our crime scene.

Someone might be buried in a certain area, the soil and the grave is gonna be looser, so that soil's gonna heat up and cool down at a different rate and we'll be able to see that with the drone with infrared.

AidanKohana asks, big question, what's the relationship between Sherlock Holmes and the development of forensic science?

Sherlock Holmes was a fictional character created by Arthur Conan Doyle, used his keen powers of observation, along with inductive reasoning, deductive reasoning, The scientific method applied to criminal investigations inspired other famous forensic scientists, notably Dr. Edmond Locard, the father of forensic science.

Created the first forensic laboratory in Leon, France.

Edmond Locard believed that anytime someone is at a crime scene, something is transferred, something is left behind, and something is taken.

And this is Locard's Principle of Exchange.

EP Security Mag, digital forensics, how does it work and why is it significant today?

Digital forensics deals with the documentation, collection, processing and analysis of data on digital devices.

It's important because it shows up on every case today.

You walk outside to get a cup of coffee, how many surveillance cameras did you pass?

We don't walk outside without bringing our cell phone with us, that's tracking us everywhere we go.

And if you drive somewhere, how many surveillance cameras did you pass?

How many traffic cameras did you pass?

How many electronic plate readers did you pass?

Embedded technology and things that surround us, started with TVs, but now it's in refrigerators, stoves, and our thermostats.

All this data could be used for an investigation.

UnfoldLabs asks, how can AI help in solving unsolved crimes?

If you have a crime scene and you have all this surveillance footage that you gotta look at, this could take hundreds or even thousands of hours.

You could take AI along with computer vision, deep learning and object recognition and train that program to look for certain objects that's part of the crime.

And what would take hundreds of hours or thousands of hours can now be done in a fraction of time.

AI's also used in other technology.

One example is the technology that we use for detection of gunshots.

This software and technology is called Shot Spotter.

Shot Spotter is a series of acoustic sensors that are set up in different areas that detect and pinpoint gunshots.

This technology uses AI to train itself to differentiate between gunshots and other loud noises.

Viewpoints Radio asks, what did detectives rely on to solve a case before forensic science was part of the toolbox?

Investigators before were doing science-based investigations use testimonial evidence, interviewing victims, interviewing witnesses, interrogating suspects, and investigating alibis.

Forensic science is objective and testimonial evidence is subjective.

Our eyewitnesses sometimes see something that's not there or miss something that was there.

Our suspects that are interrogated, they could lie and even suspects will sometimes admit to crimes they didn't even commit.

And again your witnesses may be wrong, your suspects may lie to you, but your evidence is not gonna lie.

Women In Forensics asks, how can the communication gap improve between lawyers and forensic science experts?

As a forensic scientist you have to explain very detailed, complex scientific ideas to people who don't have the same education training experience that you do.

For any case no matter how experienced you are, you always want to prep with whoever's calling you to testify.

You wanna go over questions that they might ask, the work that you did, any sort of errors that you might have made.

You want to that get that out in the open right away.

Also explain any sort of limits to the analysis that you did.

Eventually when you get to court, your testimony should be simple enough that the jury understands it.

I worked with an investigator once that was testifying and he kept saying that he was using an ocular enhancement device.

Eventually the defense attorney asked what's an ocular enhancement device?

And he said, oh, a magnifying glass.

Don't use big language, talk in simple terms.

Toolkit_masoabi, but how does forensic science solve murders that happened 50 years ago?

Just because the cases old doesn't mean that we can't solve it, that evidenced still exists, it still can be analyzed.

Maybe back then 50 years ago, we only processed that evidence with conventional fingerprint powder.

But now we could pull that evidence from storage, we could do DNA analysis on it.

We could do chemical development of fingerprints and we could use a scanning electron microscope to look at that evidence at an atomic level to look at micro traces of DNA.

Every day in the news we see cold cases, old cases being solved with new technology and advancements in forensic science.

A good example of this would be the Golden State Killer case.

You had a series of unsolved homicides and rapes that was eventually solved with new technology that is forensic genetic genealogy.

Be able to find out who a relative was of this killer and from there their investigation was this old fashioned gumshoe work.

They identified the suspect who at one time was a police officer, and eventually they wound up with a tissue that had his DNA that matched all these different crime scenes.

Lisa Licata asks, how are the bodies in the Dead Marshes so well preserved?

So what Lisa's referring to is Pete Moss bogs in Northern Europe where they have found these bodies that are preserved for thousands of years and some of them are really in amazing condition.

Normally when you die, there's a process that happens.

Whatever the surrounding temperature is, your body temperature will match that.

And that's called algar mortis.

Also, because your blood is no longer circulating your blood system, gravity's gonna pull it down and then what we see is what's called liver mortis or lividity.

Also, cuz the chemical changes in your muscles, they will temporarily stiffen, and this is called rigor mortis.

Besides these processes we have autolysis, the destruction of cells after they die.

You'll see things like skin slippage.

Your skin will darken and your cells will continue to break down, liquefy to the point, or after a period of time you'll become a skeleton.

So in Northern Europe, these peat moss bogs are actually a perfect environment to preserve a body.

They have very little oxygen and they're very acidic.

Bacteria in these environments can't grow and the body winds up being pickled.

Years ago I was involved in a case, a woman recalled her stepfather burying a body in her backyard.

40 years later, we go to that backyard, we dig up the exact location where she said the body was buried and we find in a plastic garbage bag this body and the body was really well preserved.

It still had its flesh on it after 40 years.

So sometimes you just get that right amount of bacteria or no bacteria inside of an environment and that body becomes preserved.

Rethabilejamar, is there money in forensics?

Asking for a friend.

If you're getting into forensics for the money, I would suggest pick a different career.

It's not because you'll be poor, it's just that it's hard work.

It's a difficult job to do.

You gotta spend hours looking at the same piece of evidence, looking at the same crime scene.

You gotta really love the work.

Otherwise, years of looking at this evidence or looking at these crime scenes, it's gonna feel like a prison sentence.

Well, that's it.

That's all the questions.

I hope you learn something.

Until next time.