To Catch a Cheater

Bill Mitchell has spent decades as a private investigator with an emphasis on cheating relationships.Infidelity investigator Bill Mitchell

His experience investigating infidelity led him to write a book, “The More You Know: Getting the Evidence and Support You Need to Investigate a Troubled Relationship.” (Click the link at the bottom of the page to order.)

In a Q&A with Editor Matt Allen, Mitchell outlined the biggest warning signs of a cheating spouse, how to avoid costly mistakes when trying to gather evidence, and what you should do if you suspect your spouse of having an affair. You say there are eight big warning signs that a spouse is cheating. Would you tell us about a couple of those?

Bill Mitchell: The most important is defensive behavior. That’s where the spouse is cagy. They just won’t answer your questions. They will dodge around it, try to sidestep direct questions. They always blow up in your face when you ask anything that seems relevant to a disappearing act. That’s probably evident in almost every case I handle. Defensive behavior is number one.

Another one that is very important is they will say they need to be alone or “I need my space” or “I’m not coming home tonight.” There are excuses and cancellations.

The reason you see those two together is one, they don’t want you to get close enough to what they are doing and two, they have got to find a way to get away, to disappear and not be detected.


DD: What should you do if you suspect your spouse of cheating?

BM: The first important thing is don’t break the law. I get a lot of clients who call and ask, “Can I bug her phone? Can I put a tape recorder underneath the seat in her car?”

I tell them of those things that are illegal you can’t do. You can’t wiretap. You can’t put cameras in places where you don’t have permission to do that. So right off the bat you’ve got to be really careful with what’s right and wrong in your state.

Two, you need to create a strategy. That’s a big thing for me. You’ve got to figure out what to do first, what to do second. What is your gameplan? What do you need? What do you feel you want at the end of this?

Also, don’t tell anybody. Don’t try to include people in your situation. The old adage is I can keep a secret but it’s the person I told it to that can’t.

catch a cheating spouse book

Next thing is look for indicators, such as changes in behavior. Look for items that are discoverable – records, any documents, e-mails, texts, phone calls, disappearing funds – those indicators that show something is going on that you weren’t aware of.

Some people commit financial infidelity and they’re not really cheating, they are just not telling you they are spending money or they are hiding money. In that same vain, you need to find those indicators that will prove that there is actually something going on.

On top of that you want to gather tangible evidence in the form of text messages. Print them out, save them. If there is sexting with images, get copies of those. You can install spy software on a computer to collect that data.

Also, any other evidence that was left behind. For example in one case recently, a husband got an apartment on his own, the wife somehow got a key, got in, and found a love letter signed by one of his co-workers. So that is a tangible piece of evidence; it’s solid, it’s helpful.

Use technology. In today’s world, there are lots of ways to do things where we couldn’t do years ago. For example, we can use GPS to track a car and we can figure out where that car is at any moment so you aren’t watching and waiting needlessly to follow someon. Use it because it’s fabulous technology as long as it is legal in your state.

We employ and use a lot of covert cameras that can record video for you. We’re looking for ways to prove that something is happening or it isn’t. For example, in this custody case I just finished, the husband had one of these hidden cameras in place when the wife took a swing at him. He was able to document it and it got her out of the house.

You should hire a qualified and reputable private investigator. There are PI’s in every state and county. It’s important you do a good screening before you do that. And that is covered in one of my chapters in my book.

Finally, something that should have been at the top of the list, is don’t ask. If you ask, you’ve tipped your hand and you’ve lost the card game immediately. Don’t ask until you can prove that it is happening. That’s when you can have a discussion.


DD: When gathering evidence you just mentioned don’t ask. Earlier you said don’t break the law. What are some other common mistakes people make when trying to find evidence that their spouse is having an affair?

BM: They get clumsy. They end up being irrational and emotional and attacking a situation too direct. That’s a big mistake.

You have to be careful. You have to think very clearly of what you suspect and sidestep the emotional issue because it’s a big deal.


DD: Finally, social media and online dating sites have made it much easier to cheat these days. But does it also make it easier to catch someone who is cheating on you?

BM: That’s a real good question because that is one of the first places where private investigators or lawyers go to determine whether there is anything going on. These days, text messages have been introduced as evidence almost every day of the week because it is very damaging.

It used to be about 80% of the time that “other person” in a cheating relationship was someone you worked with. Nowadays there are businesses that are thriving because of infidelity like chat rooms and other businesses where you can meet people exclusively online and you have never seen them or interacted with them before.


Click the link for a video version of the interview. To order “The More You Know”, visit

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