Rape Kit Testing

Stan Asks:

My question for you is would a rape kit routinely be used to test for evidence of chemicals found in a condom in addition to DNA or would further tests be required? My plot has a woman getting even with a man by having her girlfriend have sex with the guy (he’s using a condom). She then gives the material to her friend who applies the sperm and claims she was raped.

Amryn Says:

Rape kits are routinely tested for the presence of semen and sperm and maybe saliva depending on the story the victim gives. Chemicals found in spermicide and other condom components aren't something an analyst would test for. Depending on how long of a time lapse between intercourse and the woman applying the sperm, it's possible the spermicide on the condom would have already degraded the sperm to the point that it isn't detectable, but that would only occur after a long time.

 More likely, when DNA testing was performed, it would yield a mixture of 3 profiles: the man, the woman's friend, and the woman. This is because the woman's friend's profile would likely be present on the condom from the intercourse she had from the man. This might raise a red flag but it would be up to the investigator to look into it further.

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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 andFacebook.

Forensic Question: Solving Cold Cases

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 on Amazon. Look for Warzone in January 2015. You can connect with Amryn via her website, Twitter and Facebook.

Forensic Question: DNA Testing Turn Around Time

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

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.

Genetic Haemochromatosis: The Silent Killer

Genetic Hemochromatosis (GH) is a hereditary disorder causing the body to retain the trace mineral iron over and above its requirements. Without iron we couldn’t survive – its instrumental in the transportation of oxygen around the body; but too much iron kill. As the body cannot expel excess iron, it deposits it around our organs — mainly in the liver, pancreas, heart, endocrine glands, and joints, where it turns into a poison.

The subject is close to my heart, having been diagnosed with Genetic Hemochromatosis 10 years ago. I decided to write a humorous spoof thriller to increase awareness, raise funds and bring humor; I believe laughter is the best medicine. ‘The Unexpected Consequences of Iron Overload,’ is a paranormal, romantic, spoof thriller, with 100% of profits being donated to the Hemochromatosis Society.

Jimmy has absorbed iron and is now magnet. After a significant event in which he saves Barbara, the woman of his dreams, from possible death Jimmy realises he can control his magnetism. His life is further complicated after coming to the attention of the KBG - they are interested in all things paranormal, and the CIA who are determined to stop the Russians. Sheila further complicates life for Jimmy. Her father is Irish though she was born in Australia. Unbeknownst to her she has Haemochromatosis and is magnetic but of course, from the Southern hemisphere her polarity is reversed. 

For a disorder that few have heard of, it is surprisingly common. In Europe an estimated one in 200 have the genes linked to it — that’s 3.7 million people.  The Hemochromatosis Society — a charity founded and chaired by Janet Fernau, MBE says “people are suffering from entirely preventable diseases and even facing premature death because of a lack of awareness and testing.” 

Left untreated, this insidious condition causes individuals to develop life-threatening illnesses like diabetes, liver cirrhosis, cancer, arthritis, and heart disease.  The treatment is simple and cheap. The only way to remove iron from the body is via the blood - venesection.  Every pint removed takes with it 200mg of iron and lowers ferritin levels by 25 as the body starts to use the excess stored iron to make new red blood cells.

Hemochromatosis Society - www.haemochromatosis.org.uk – has as host of resources for people who have the condition.

The preface to The Unexpected Consequences of iron overload is a good layman’s introduction to the subject. In addition, a list of worldwide support groups/resources are included in my book.

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At age 52 James Minter was diagnosis with hemochromatosis. He is one of the lucky ones: he found out in time, and has no long-term organ damage. Researching the condition, he discovered there are millions of people who are carriers or have the disorder. The majority are unaware. The opportunity to stop unnecessary suffering is great. As a fiction writer in the humor genre, James wanted to use his creativity to bring hemochromatosis to the fore. He wrote The Unexpected Consequences of Iron Overload.  This is a light-hearted paranormal, romantic, spoof thriller with a serious message. Using the book he spends much of his time raising awareness of hemochromatosis via social media, blogging, presentations, press releases and radio interviews.

Forensic Topic: DNA Analysis

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.