Amryn Cross

Author Forensic Question: Evidence of Pregnancy on Autopsy

/ Jordyn Redwood / Leave a comment


Aray Asks:

Can an autopsy show evidence of a three week old fetus? I’m researching for a novel I’m writing and I need your help, considering that the information has to be accurate.
My MC’s mother’s body is severely mutilated ( carved into).  She was three weeks pregnant at the time this gruesome murder took place. Police officials accuse her husband of doing the deed.  Having no leads, they arrest him. The husband’s on trial for capital murder.  The medical examiner takes the witness stand. The lawyer asks him a series of questions, one being the autopsy report.
Amryn Says:
A 3 week old fetus would not be visible during an autopsy. At that point in development, the fetus is a ball of cells but without any physical characteristics that one would recognize as human. If the medical examiner needs to detect that the victim was pregnant, the best way would be to perform an HCG test on the victim’s blood.
HCG is the hormone that is responsible for making a pregnancy test appear positive. It usually takes 3-4 weeks for this hormone to be at a high enough level to trigger a positive test, however a quantitative test might be enough to suggest that the victim’s hormone levels were slightly above normal. I wouldn’t think it would be enough for a medical examiner to definitively say the victim was pregnant, but it might be enough for he/she to say it’s possible. Any time after 4 weeks, the HCG levels will begin to rise almost exponentially and therefore would be more easily detected.  

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Amryn Cross is a full-time forensic scientist and author of romantic suspense and mystery novels. Her first novel, Learning to Die, is available on Amazon. The first book in her latest series, loosely based on an updated Sherlock Holmes, is available for pre-order on Amazon. Look for Warzone in January 2015. You can connect with Amryn via her website, Twitter and Facebook.

Author Forensic Question: Planting DNA Evidence

/ Jordyn Redwood / Leave a comment

Question:

I’m considering writing a crime novel that involves the antagonist framing others for crimes he has committed. He is a genius level sociopath who studies his victims’ habits by analyzing their trash.  His day job is with the local trash company (handy for him.)

Now the question. Can he use semen from a condom (if it’s not too old) to plant on/in a victim? He rapes, kills, and then plants the evidence along with other clues that lead to his intended second victim?

Amryn says:

This is a great scenario for a novel and would certainly throw the police off for a while. For the antagonist to pull this off, he will need to take some precautions. First of all, if he rapes the victims himself, he’ll most certainly need to wear a condom. Secondly, how he kills his victims will be important in determining if he’s left any of his DNA behind. For instance, if he strangles them with his bare hands, it is possible his DNA could be found from a swab of the victim’s neck. The use of a knife would run the risk of cutting himself and leaving his own DNA behind that way.

As far as planting the evidence, that’s certainly possible. In fact, the reverse of this has been done in real life. A man was put in prison for rape, largely because of the DNA evidence against him. While he was in prison, he placed some of his semen in a ketchup packet and smuggled it out to a female friend. She then planted the semen on herself and said she’d been raped. When they collected the evidence and processed it, the DNA came back to the man who was in prison—a pretty good alibi for the time of the rape. He insisted that the DNA results must have been wrong in the first place or someone else had his DNA profile. Of course, his scheme didn’t work, and as far as I know, he’s still in prison. All that to say, yes, planting that sort of evidence is definitely possible.

If your antagonist takes the condom from someone else’s trash, he runs the risk of having another person’s DNA present as well. When things are thrown away, DNA from several sources (presumably everyone who lives in the house) will come in contact with other objects and transfer will happen. There might not be significant enough transfer to matter, but it could result in the bad guy inadvertently transferring the male’s DNA as well as his partner’s DNA to the victim. If that’s his intention, there’s no problem, but it could also provide a way for your hero to figure out that something just doesn’t seem right about this.

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Amryn Cross is a full-time forensic scientist and author of romantic suspense and mystery novels. Her novel, Learning to Die, is available on Amazon. The first book in her latest series, loosely based on an updated Sherlock Holmes, is available for pre-order onAmazon. Look for Warzonein January 2015. You can connect with Amryn via her website, Twitter and Facebook.

Forensic Question: Solving Cold Cases

/ Jordyn Redwood / Leave a comment

My question is about cold cases. Are you able to test for DNA from blood on a knife or clothes from 30-40 years old? Also, if the remains of a body were found in a mine shaft, could you tell the manner of death from that same time or even older, say, 150 years old? How would you do this and how long would it take? Thanks so much for your help!
Amryn Says:

Cold case investigations have come a long way with the use of DNA technology. Answers that would have been impossible 20 years ago are now commonplace. The problem with cold cases is often in the handling of the evidence. On the knife or clothes that you mentioned, when they were first collected from a crime scene 30-40 years ago, the investigator may not have worn gloves. That seems shocking given what we know now, but it wasn’t all that routine a few decades ago.

What that might mean for your DNA results is that you get a mixture—say, the victim’s blood and another unknown profile. Now, does that profile belong to the killer or just the detective or crime scene tech that handled the evidence without gloves? Without something to compare back to, you won’t be able to say.

Let’s assume best case scenario, though. If the bloody evidence was stored and handled properly, it is definitely possible to get a DNA profile from the blood present on a knife or on clothes. This can usually be done with routine DNA testing, which generally takes 2-3 weeks. Of course, for the purposes of fiction, the DNA could be “rushed” and then results would possibly be available as soon as 48 hours. This testing will probably be done at the police department’s or state’s crime lab.

As far as a body in a mine shaft, unless the body is frozen, it’s likely to be not much more than a skeleton by the time it’s found 30-40 years later, and certainly 150 years. However, if the manner of death was some sort of trauma (i.e. broken neck from a fall or stab wound where the knife grazes the bone), a lot can still be determined from bones.

In most cases, a forensic anthropologist would be the person to make that determination. Some states have one on staff while others call in an expert like Dr. Bass (founder of the Body Farm) when they are needed.  I would say the time frame for that sort of determination is at least a couple weeks, though I’m sure there are cases where it could be done faster. And I should also mention, many forensic anthropologists like to be present when the team is recovering the bones to make sure none are missed and to make observations based on the position of the bones.

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Amryn Cross is a full-time forensic scientist and author of romantic suspense and mystery novels. Her first novel, Learning to Die, is available on Amazon. The first book in her latest series, loosely based on an updated Sherlock Holmes, is available for pre-order onAmazon. Look for Warzonein January 2015. You can connect with Amryn via her website, Twitter and Facebook.

Forensic Question: DNA Testing Turn Around Time

/ Jordyn Redwood / Leave a comment

Amanda asks:

How long does it typically take for DNA results to come back in a murder case, specifically blood on a knife? Could the agency get a preliminary report (i.e. blood type) any faster?

Amryn says:

Each lab will have its own turnaround time for DNA. For most state crime labs or local agency labs (meaning those that are attached to a law enforcement agency) the turnaround time is likely to be several weeks/months. This is because they may receive dozens of cases per day, certainly per week, and cases are usually worked in the order they are received. Some cases may only have one or two samples that need DNA testing, while others may require 40 or 50 (this is not as common, but not unheard of either.)

In some cases, a district attorney or someone in charge of the lab may declare the case a “rush” or an “expedite” (usually documented in the form of a letter), in which case it jumps to the front of the line. A lab may drop everything else to work on this case, depending on the scope of the case. Usually one analyst is assigned a case, but may ask others for help to get the results out faster.

Best scenario (which never happens), DNA could possibly be done on an exhibit as small as a knife in 48 hours. Then the report has to be reviewed by two other analysts before it can be sent to law enforcement. That’s not including a search of the FBI database if there are no suspects in the case. A manual search of the database may be done in rare cases, otherwise it’ll take another week to see if the DNA profile “hits” anyone in the database.

Most places don’t do blood typing anymore because it’s kind of time consuming and obviously not as unique as a DNA profile. The most that could be said in a preliminary report is to verify that the stain on the knife is, in fact, blood. It seems silly, but they do have to verify that it is blood and not cocktail sauce or something on the weapon.

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Amryn Cross is a full-time forensic scientist and author of romantic suspense novels. Her first novel, Learning to Die, will be released in September. In her spare time, she enjoys college football, reading, watching movies, and researching her next novel. You can connect with Amryn via her website, Twitter and Facebook.

Forensic Question: Differentiating Twin Murder Suspects

/ Jordyn Redwood / Leave a comment
Sarah asks:
If you have identical twins who are both suspects in a murder, how could you tell them apart?
Amryn says:

Identical twins are a hot topic in forensic DNA. Up until now, it’s been thought that identical twins have identical DNA and therefore are the perfect twist to a murder mystery. We’re finding out now that’s not necessarily true.

Strictly from a DNA perspective, research is showing that even twins have small minute differences in their DNA called SNPs (single nucleotide polymorphisms.) These aren’t routinely tested for in forensics because they’re pretty cutting edge, but such testing could be done (likely by a private lab) if the need arose.
Another option would be generating an antibody profile. When we’re born, we have an antibody profile like our mother. But beginning at birth and until the age of two, our antibody profile is evolving. It’s pretty much set in stone by the age of two and (as far as we know) doesn’t change throughout life. These antibodies are slightly different than the ones you make to fight off disease, but the important part is that they’re unique. Even identical twins will have different antibody profiles. This testing is new and is beginning to be used in conjunction with DNA testing.
Of course, this all depends on what type of evidence is found at a crime scene. Antibody profiling might be useful if some type of body fluid is found (i.e. blood, saliva, tears, sweat, etc.) but not so much with skin cells or hair. And, of course, even identical twins should have different fingerprints, so in a case such as this, DNA evidence might not be as strong as some other possible links.
If you’re interested in learning a bit more about antibody profiling, check out this article: http://www.americanlawyeracademy.com/antibody-profiling-forensic-evidence
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Amryn Cross is a full-time forensic scientist and author of romantic suspense novels. Her first novel, Learning to Die, will be released in September. In her spare time, she enjoys college football, reading, watching movies, and researching her next novel. You can connect with Amryn via her website, Twitter and Facebook.

Forensic Question: DNA Analysis

/ Jordyn Redwood / Leave a comment

This question came to me via my blog as a comment but for some reason didn’t post so I put Amryn to the task of answering it but am only using the poster’s initials since she didn’t give permission directly to use her full name.

It is related to Amryn’s post on DNA analysis that you can find here.

S.C. Asks:

I understand that it becomes more difficult with half-siblings. But with full-siblings, if say, a brother suspected that someone was his sister, could he, through a blood sample, confirm the lineage if he did not have access to the parent’s DNA?

Amryn Says:

This would definitely be possible. The best way to go about it would be to do mitochondrial DNA testing which traces the mother’s lineage. So a brother and sister would have the same mitochondrial DNA because they share the same mother. To try to connect two people as siblings with the more common type of DNA testing is more difficult and would involve statistical calculations. The chance that full siblings will share one of their numbers (see the example in the post) at one of those locations on a chromosome is about 50%. So, yes, the brother could determine someone was his sister, but his best bet would be to have a mitochondrial DNA test done.

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Amryn Cross is a full-time forensic scientist and author of romantic suspense novels. Her first novel, Learning to Die, will be released in September. In her spare time, she enjoys college football, reading, watching movies, and researching her next novel. You can connect with Amryn via her website, Twitter and Facebook.

Amryn Cross: How to Research Your CSI or Detective

/ Jordyn Redwood / Leave a comment
Unless you’ve been living under a rock these past few years, you’ve probably seen an episode of the dozens of forensic type shows on television—all the varieties of CSI, NCIS, SVU, etc. They make the job look gritty and glamorous but hardly ever real. It makes for great entertainment, but not a lot of truth. This can be troublesome when you try to base your latest crime novel off something you’ve seen on television. 
Any writer writing outside their field of expertise knows some research is going to be involved, but in a field like forensics, it’s easy to be overwhelmed by the amount of information out there. I’ve compiled a short list of questions to get you on track when researching your CSI or detective character.

1.       Where does your story take place?

This is big one. If you’re going for authenticity, it’s better to narrow down your search to the area you’re looking at. For instance, New York City isn’t going to have the same structure to their police force or crime lab that a small town in the Midwest might have. If you’ve got a fictional setting, the good news is you can take bits and pieces from several places and make your own rules. Especially larger cities will have a website for the law enforcement agencies that might post job opportunities or a list of departments with descriptions. Utilize those.

2.       When does your story take place?

This may go without saying, but if your story is set in the 1980’s or 1990’s, having your detective catch the bad guy with DNA is not very believable. Technology and tests are always changing in forensics.

3.       What’s your character’s job title?

As cool as it looks on CSI, I can’t think of a place where the same person collects the evidence at a crime scene, determines the cause of death, runs the test on the evidence, interrogates the suspect, goes on stakeouts/undercover ops, and make the arrest. There are different jobs for each of these, and overlap will vary from place to place. In a small town, a detective might collect the evidence, interrogate the suspect, and make the arrest, but he or she won’t be determining the cause of death (that’s the medical examiner or coroner) or running the tests on the evidence (if it’s a small town, the evidence will probably be sent to the nearest crime lab.) At the same time, your CSI may collect evidence and nothing else if they work in a large city. Other places, the same people collect the evidence and test it.

4.       What agency does your character work for?

Research that specific agency and know what they specialize in. Most law enforcement agencies will work a variety of crimes, but many people are surprised to know that the FBI doesn’t typically get involved in murder cases or witness protection even though they’re often depicted doing just that. Find out how people within that agency are titled. Are they detectives, agents, inspectors, officers? Who carries a gun within that agency? You might be surprised. In some states, even the lab personnel are considered commissioned officers and carry a weapon.

5.       Don’t be afraid to ask questions.

There are lots of experts out there who are willing to answer questions about their experiences (myself included.) Most law enforcement agencies have a public relations person or department that can answer some questions for your specific region. One of my favorite online sources is the Crime Scene Writer’s group. This is a pool of people from all sections of law enforcement who are willing to answer writer’s questions. Make sure you search the messages first because there’s a lot to be gleaned from past questions.

Researching your law enforcement character doesn’t have to be scary. When in doubt, ask.
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Amryn Cross is a full-time forensic scientist and author of romantic suspense novels. Her first novel, Learning to Die, will be released in September. In her spare time, she enjoys college football, reading, watching movies, and researching her next novel. You can connect with Amryn via her website, Twitter and Facebook.

Forensic Author Question: Fetal Bones

/ Jordyn Redwood / Leave a comment


This month, Amryn has another great author question to answer.
Gloria F. asks: At what fetal age would bones show up with mom’s if mom was killed & stuffed in locker for 15 yrs? The body has been above ground in a disused bldg for that length of time.
Amryn says:
It’s important to understand that there are always exceptions to every case, so the answers I give are generalized unless otherwise stated. That being said, there are a couple factors at play here.
First of all, the process of skeletonization will vary with temperature and humidity. In this case, 15 years would be sufficient time for both the mother and the fetus to be skeletonized. This process can actually take as little as a few weeks in a hot humid environment. This is the sort of research done at the Body Farm (see my previous post for more info.)
A fetus will begin to develop its skeletal system around 12 weeks. From that point forward, the bones will grow harder and more dense. Theoretically, you could find fetal bones as early as approximately 15 weeks of gestation. The problem with this is, the bones are not fully articulated and would be very easy to scatter. Also, if you consider the average size of a fetus at 15 weeks, it only measures about 6 inches long. Those are some very tiny bones!
That’s not to say they couldn’t be detected by an anthropologist or medical examiner, but I would guess it’s more likely to find them if they suspect the woman may have been pregnant. Obviously the larger the bones, the easier they’ll be to see.
Another thing to consider is the idea of coffin birth or postmortem fetal extrusion. Basically, as the woman began to decompose, gases would build up in her body and could force the baby from her uterus… almost as if she was actively giving birth. This articleexplains it well. It’s something to consider as the fetal bones may not be found “inside” the woman when her remains are discovered.
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Amryn Cross is a full-time forensic scientist and author of romantic suspense novels. Her first novel, Learning to Die, will be released in September. In her spare time, she enjoys college football, reading, watching movies, and researching her next novel. You can connect with Amryn via her website, Twitter and Facebook.

Forensic Topic: DNA Analysis

/ Jordyn Redwood / Leave a comment

I’m so pleased to have forensic expert Amryn Cross back with a question from a reader.

Welcome back, Amryn!


S.H. posed the following question about DNA analysis:
In my book, an investigator has a DNA test done on some samples and two profiles are found. The profiles are for half siblings, a man and a woman, who share the same father but different mothers.
What I need to know is this: Could they tell from just the brother and sister’s DNA that they are half siblings? I know they could probably tell that they’re related, but how clear would the match be? Would it be possible to say they share the same father? Or would they need to take a sample from dad to indicate that both were likely to be his children?
This is a great question about what can and can’t be gained from DNA testing. The tests performed in most crime labs will look at a set of 13 markers plus an additional marker to determine sex (amelogenin). For each of these 13 markers, a person will have two numbers. For instance, at marker number one, person A might have the numbers 10 and 13. We would say that their profile at that marker is a 10,13.
Using basic genetics, we know that a person inherits one of these numbers from the mother and one from the dad. In the above example, person A’s mother might have been 10,11 and the father might have been 11, 13. In that case, person A inherited the 10 from the mother and the 13 from the father. As you can imagine, this gets quite complicated when you have to look at several sets of these numbers which make up a DNA profile.
If you compared the profiles of a mother and her son or daughter, they would have at least one number in common at each of these 13 locations. If you also had the profile of the father, you could see that the child would also share at least one number with him as well. But for a brother and sister, things get more complicated. Look at this example:
Mother: 10, 11
Father: 13, 14
Son: 10, 13
Daughter: 11, 14
As you can see, each child received one number from their parents, but the brother and sister don’t share any numbers. Therefore, it is possible that we wouldn’t suspect they were related based on their DNA profiles. If you throw half-siblings in the mix, it becomes even less likely that the connection would be recognized if you didn’t have a reason to suspect it in the first place. It is possible that half-siblings would share no markers or at least not any more than unrelated people.
If you had the father’s DNA profile you would likely be able to say that he’s possibly the father of both, but not definitely. There are statistical calculations that can be done to help determine the degree of relatedness. Special testing of the Y chromosome would be able to tell that the father and son are definitively related but wouldn’t be helpful with the daughter.
As a side note, many crime labs won’t do paternity testing, and if your investigator didn’t already suspect these two people to be siblings, he would have a hard time getting a warrant for the father’s DNA profile. Of course, if the father willingly provided it, a comparison could potentially be made.
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Amryn Cross is a full-time forensic scientist and author of romantic suspense novels. Her first novel, Learning to Die, will be released in September. In her spare time, she enjoys college football, reading, watching movies, and researching her next novel. You can connect with Amryn via her website, Twitter and Facebook.

The Body Farm

/ Jordyn Redwood / Leave a comment

Forensic specialist Amryn Cross is here for her monthly post on that elusive Body Farm.

Welcome back, Amryn!


Today I’m answering a question from an author who wished to remain anonymous.
I’d like to for my character to visit the Body Farm as part of their investigation. What is it really like?
First, let me preface this by saying that I haven’t actually been inside the Body Farm (technically known as The Forensic Anthropology Center at the University of Tennessee), but I can offer some insight on the facility. There are several good websites (http://fac.utk.edu/) and even a documentary out there, so I won’t try to cover the topic extensively. 
The Body Farm is a little over 1 acre situated behind the University of Tennessee Medical Center. The collection of skeletons (nearly 1000) is one of the largest in the world, and is housed under Neyland Stadium and in the Forensic Center below UT hospital. Once the bodies placed on the Body Farm are skeletonized and have reached the extent of their usefulness, many of them are transferred to the collection for further study.
When your character approaches the Body Farm, they’ll notice it’s located in the back of the UT hospital employee parking lot. It’s surrounded by wooden and chain length fences with barbed wire around the top. The area beyond this is hilly and covered with trees. 
Beyond this point, human bodies in various stages of decomposition are placed around the campus. Some exposed to the elements, others inside a car or concrete structure. Few are buried at various depths. All this is to allow the staff to study and measure the markers of decomposition. During the summer, the smell of death is ripe, even outside the fence. I had the dubious honor of parking in front of the Body Farm during my year of clinicals at UT hospital. Definitely an interesting experience.
The Body Farm is also used to educate law enforcement personnel as it is an integral part of the National Forensics Academy. The NFA hosts law enforcement agencies from all over the country to teach them proper techniques in forensic death investigation. This includes a crime scene with an actual body donated to the facility.
Though the facility at UT was the first of its kind, there are now four facilities in the US—University of Tennessee, Western Carolina University, Texas State University, and Sam Houston State University.
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Amryn Cross is a full-time forensic scientist and author of romantic suspense novels. Her first novel, Learning to Die, will be released in September. In her spare time, she enjoys college football, reading, watching movies, and researching her next novel. You can connect with Amryn via her website, Twitter and Facebook.