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7 investments worth every penny for law enforcement investigators

Simple tips, tools and services to help detectives crack cases


From extra notepads to handheld recording devices, there are many investments detectives can make to improve their investigations.

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You’ve joined the detective bureau and are wondering what gear you’ll need to be successful. If you haven’t realized it yet, real detective work lacks the excitement typically portrayed in movies and television. As such, nothing on this list is particularly sexy but they can help you get the job done.

1. Extra notepads & pens

It seems like you never stop taking notes as a detective, so you can never have too much paper with you. Keep extra pads in your car, your desk and your go-bag.

I always use a separate notepad for each case otherwise you’re constantly thumbing through looking for that number you know you wrote down but can’t seem to find.

2. Training

Criminal investigation techniques are constantly changing as society and criminals evolve. Ongoing training is the only way to keep up. Check your local training centers or for the latest offerings.

Cell phone technology and genealogy DNA tracing are just a couple of things that have changed criminal investigations dramatically in recent years. The only way to stay current is to be constantly learning.

3. Handheld recording devices

Interviewing witnesses and potential suspects is the lifeblood of investigations. As a detective, you will spend a good chunk of your time talking to people trying to learn what it is they know or don’t know about your case. Having a recording device available is a must for a couple of reasons.

First, it allows you to focus on the person you’re interviewing instead of your notepad. If you’re constantly writing down what you are hearing, you’ll miss out on what the person’s body language is telling you about their statements. For example, the suspect who can’t make eye contact when asked a direct question about their guilt or the trauma victim who starts to shake as they recount their experience.

The second reason is that you need to be recording your suspect interviews. Nothing beats playing a suspect’s own words for a jury. It also prevents the defense attorney from alleging that you twisted a client’s words to make your case.

You could always use an app on your phone but make sure it’s a work-only phone to avoid any personal data being handed over to the defense.

4. 10-21 Police Phone app

The 10-21 Police Phone app by Callyo is geared toward law enforcement with a variety of features; one of the most useful is that it allows you to spoof your phone number. You can set it to identify you as law enforcement, but I’ve found it most useful in concealing my identity from suspects. One way it does that is to generate a local number for whatever number you dial.

So, if you’re calling someone out of state or even just another nearby area code, the caller will see a local number that will hopefully increase the chances of them answering. Cellphones play such an important role in investigations nowadays that simply confirming who uses a particular phone is enough to make some cases.

5. Books

You can never have too much knowledge, and books are an effective way of gaining that knowledge at a reasonable price on your own schedule.

Here are a few I would suggest to a new detective looking to learn:

  • Practical Homicide Investigation: Tactics, Procedures, and Forensic Techniques by Vernon J. Geberth. This is commonly referred to as the bible for homicide investigators and for good reason. It covers every aspect of death investigations with an emphasis on proper crime scene protocol and attention to detail. If you had to pick only one book off this list, this should be it.
  • I Know You Are Lying by Mark McClish. When we speak or write something, we are making a cognitive choice to use those words in that combination, and we are making that choice based on our knowledge of what happened. This book helps to explain statement analysis and how it can be helpful in determining if someone is being truthful or deceptive with you.
  • Violence: Reflections on a National Epidemic by James Gilligan, MD. Written by a prison psychologist, this book looks at why violent offenders are violent in the first place and the role shame plays in causing offenders to act out violently. You can’t effectively investigate violent offenders unless you understand why they do what they do.
  • Ghettoside: A True Story of Murder in America by Jill Leovy. This book looks at investigating homicides in a Los Angeles neighborhood where death is too common for both the residents and police officers who live and work there. The biggest takeaway for me was the difference that one dedicated and relentless detective can make in finding justice.
  • Child Molesters: A Behavioral Analysis by Kenneth V. Lanning. If you are ever called upon to investigate sex crimes involving children, this is an invaluable resource to help you better understand the psychology of child sex offenders. Best of all, it’s available for free online.

6. Investigation software (an agency investment)

Some criminals just don’t want to be caught. Investigation software can help you with that problem by helping you to efficiently search thousands of public databases with a few keystrokes. A suspect’s parent’s address, a phone number they only gave the cable company and out-of-state arrests are just a few things you can turn up.

There are several companies out there with a variety of price points depending on your needs, but if you’re going to do a deep dive into someone’s background looking for that missing link, your agency is going to want you to have this tool. Start your search with Police1’s free eBook: How to buy investigation software.

7. An on/off switch for yourself

The final suggestion I would make is learning to hit the off switch when you leave the office. Many of your cases will take weeks, months and sometimes years to conclude, especially when you factor in the court process. One of the things I miss most about patrol was that once the day was over, you were mostly done working until the next shift. Investigations is a different animal, and if you don’t turn it off, the stress will eat you up.

Those are my suggestions to get you started. What would you add to the list? Email to submit your ideas.

Police1 reader suggestions

  • A cellphone with a good, high-resolution camera. Sometimes you have to get your pictures quickly and you might not have a camera available.
  • Physical attendance at post-shooting training as much as you can get. Many officers manage to complete their careers without ever having to take a human life in defense. I was involved in a fatal shooting as a patrol officer and later as a detective. The post-shooting classes that my department sent me to paid off in spades when as a detective, I investigated self-defense shootings, both officer-involved and private citizens.
  • Mindfulness training and DBT-type therapy. This could potentially address any unknown underlying triggers and mental health issues for the investigators (which ALL of us humans have from time to time), as well as giving the investigators an honest edge on how to be effective, dealing with folks who may be afraid, unwilling or even emotionally disconnected, allowing more opportunity to be aware of unneeded damage and facilitate healing when possible. This type of awareness and training is, in my opinion, the most essential set of tools for being effective, inclusive and kind. This type of intentional awareness will allow investigators to be more prepared and connected.

Detective Corporal Jim Twardesky has been in law enforcement since 1999, currently serving as a detective for the City of Warren Police Department in Michigan. He has a bachelor’s degree in criminal justice and a master’s in public administration, both from Wayne State University. Additionally, he teaches as an adjunct instructor for the Macomb Public Service Institute and regularly lectures on the subjects of child homicide, sex crimes and interviewing child molesters through his company Twardesky Consulting.