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Citizens Police Academy-week 5: crime scene squad

Narcotics and Crime Scene Investigation! My manuscript SLOW BURN featured a DEA agent hero, and I absolutely loved learning about that world, so listening to the narcotics officer was fascinating. If a bit scary.

However, I know all you really want to hear about is the forensics stuff. In Fairfax County, the crime scene squad is made up of sworn police officers. No straight-from-a-master’s-in-forensics newbies here. Ideally they have at least six years on the police force before moving to the CS squad.

The first year is all on-the-job training where they can only handle evidence under direct supervision. They also spend a lot of that first year taking classes or seminars when the budget allows. The second year, they can work a scene but are still under the supervision of an experienced CS officer.

The crime scene squad investigates all major crimes like murder, rape, assault, robbery, high-value burglary, police-involved shootings, and other death investigations (suicide, accident, suspicious death). The CS crew collects the evidence; the medical examiner determines the cause and manner of death.

Causes: shooting, strangling, stabbing, fall down the stairs, drug overdose, cancer, etc…

Manners: suicide, homicide, accidental, natural, undetermined/unclassified.

The county also trains patrol officers in CS techniques so they can handle the “lesser” crimes–like burglary–themselves. This supplemental group can also be called in when extra manpower is needed to work a large or complicated scene. And of course, they’re a ready-made group of future CS candidates.

Forensic photography is the bread and butter of CS. These guys are very skilled photographers with sophisticated equipment. Our officer even showed us a photo he took at night with no flash. It was clear as day. Every enhancement made to a photo is tracked and can be reproduced by someone else.

Takeaways

  • An “average” homocide requires 12-15 hours of initial work and 500-1000 photos, starting with the macro level and working in. Each piece of evidence is photographed with and without a ruler, and often from multiple angles.
  • Crime scene diagrams can really help a jury make sense of the scene and how the crime played out.
  • At a scene, if something’s out of place, it’s evidence.
  • Footwear impressions are very useful. Most criminals wear their most comfortable shoes and are unlikely to discard them after a crime. The wear pattern will be unique to that pair of shoes if they’re at least a few weeks old.
  • They really can match up tools to tool marks, and even a saw to the bone it cut through. (Yuck!)
  • Luminol only works in the absence of light (unlike on CSI where that wouldn’t be very interesting to watch). It does require an orange filter though. Bodily fluids will fluoresce, but so will a coffee stain. That’s where the lab techs come in.
  • Which is more definitive evidence? Fingerprints or DNA? The answer is fingerprints! Surprised? Here’s why:
    • DNA can very effectively exclude a person (as with the guys being released from jail based on DNA evidence), but it can’t inconclusively identify a suspect. The odds are small, but the source of the DNA might be someone else, even if there’s a match.
    • DNA is also very easy to contaminate with multiple samples. If five people put their hands on a doorknob, you might get a mixed mess with the DNA, but all you need is one clear fingerprint to positively match to a suspect.
    • Identical twins can have the same DNA, but they will not have the same fingerprints.
  • I’d thought that paper might be a difficult material from which to get fingerprints, but apparently it absorbs the lipids, thus making for excellent fingerprint recovery. Check fraudsters take note!
  • And if you’re going to commit a crime, don’t leave the latex gloves behind. They can pull the fingerprints and DNA from the inside of the gloves.
  • Plastic used to be a difficult surface to fingerprint, but no longer. With a chemical called Rhotamine G6 and a very expensive, very precise laser (532nm) they can lift fingerprints from a shopping bag or a dime bag. And in an ironic twist, this was paid for with seized assets (read: drug money) provided by the narcotics squad to help CS work narcotics cases.

Being that Fairfax County is close to the terrorist target also known as Washington, D.C., the forensics folks at FCPD have started IED (improvised explosive device) training. The explosives team (coming soon!) rigs up an IED to a stationary vehicle and detonates it. Then the crime scene squad has to collect as many bomb pieces as possible, try to reconstruct it, and look at other evidence (direction of blast, etc…) to determine what type of bomb it was.

So that’s week five in a very large nutshell. Questions?

0 Comments

  1. Reply

    No questions, Gwen, but this is fascinating stuff.

    This was new to me –
    Identical twins can have the same DNA, but they will not have the same fingerprints.

    Thanks so much for sharing your experiences.

  2. Reply

    Fascinating, thank you! And I would love to hear about the Narcotics part of this class. CSI is interesting, but that doesn’t mean narcotics isn’t. 🙂

    • Reply

      No problem, Kathy. It’s as much a reminder for myself as a resource for others. Look for my Robbery Squad post on Sunday. Another fascinating speaker!

  3. Reply

    Hmm is anyone else experiencing problems with the
    images on this blog loading? I’m trying to determine if its a problem on my end or if it’s the blog.

    Any feedback would be greatly appreciated.

    • Reply

      Sara: Do you mean the header image and sidebar images, or even images in the posts? This particular post doesn’t have any images (no interesting shots from that lecture I guess). Could be that your connection is slow right now. We have the same problem at our house. Sometimes it’s great, other times slow as a snail. 🙂

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