Almost everyone has been in a situation where they think their partner might have his or her hand in someone else’s cookie jar. And while catching the guilty party in the act can sometimes mean snooping on their phone or reading their e-mails, some players play so hard that the evidence is almost impossible to find.

That’s where Barbara Wolford, a licensed investigator at Kinsey Investigations in Los Angeles, and Daniel McBride, president of American Eagle Investigations in New York City, come in. Here’s how they solve one of life’s most frustratingly common mysteries—the case of the cheating lover.

So You’re Thinking of Hiring a Private Investigator…

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Wolford points out that not all of these cases end in “ah-ha’s!” though.

“I had a case where a man claimed he went golfing starting at 4 p.m.,” she says. “It was in the winter and got dark around 5, so his wife was very suspicious. But, indeed, he was golfing with three other men in the dark at a well-lit golf course, smoking cigars the entire time.”

Dang, that’s cold!

RELATED: 10 Weird Facts About Cheating

Photo evidence is the best proof, and Wolford is quick to provide that to the partner who hired her after it’s obtained. “We provide still photos and any film we capture,” she says. “We never confront the cheating party, though. And I don’t make any judgment calls. I get the footage, give it to the client, and let the client decide what to make of it.”

Clues Someone’s Cheating

Suddenly working late all the time and using the computer or the phone more frequently than normal can also be tip-offs, says McBride. “If he’s guarding his phone and always has it on him so nobody can look at it—that can be suspicious,” he says. “Or if he puts a code on his phone if there wasn’t one before or deletes his text messages or incoming calls. … Also, if the husband doesn’t want to have sex with his partner anymore or his sexual desires change suddenly, that’s a big sign.”

Wolford and McBride also say that if you strongly suspect your partner is getting something on the side, the odds are, you’re probably right. “Four out of five times, the person is cheating,” says Wolford.

McBride states a higher, scarier number: “It’s about 85 percent of the time when a woman suspects her significant other of cheating,” he says. “People come to us if they have a very strong suspicion.”

…oh f*ck….

So Is Ot Worth it to Hire an Investigator?

So if you’re just feeling a little jealous, might be better to start an open dialogue with your partner about your concerns—and solve this mystery together.