A private investigator on the most disturbing thing he's noticed about people who cheat.

“One man wanted to know if his partner was up to something because she lived in another state,” private investigator Lachlan Jarvis tells me over the phone.

“So we surveyed her… she came out of the house with another man, and she was in a relationship, but over the course of a few days, not only did we see that, we also saw her robbing houses.

“She had lied about an illness she claimed she was having, that he was helping pay her medical bills for.”

The woman, Jarvis tells me, also had an STI she had not disclosed to her partner. Jarvis said it’s just one example of many of the disturbing “pattern on behaviour” he’s observed in people who cheat.

When I interviewed Jarvis, who works for Lyonswood Private Investigators and Forensic Group, I was interested to know whether he ever worries that cheating is the type of thing that’s best kept a secret. What we don’t know can’t hurt us – right?

Esther Perel, a renowned relationship psychologist, argues that we need to rethink infidelity. In fact, she says our prior indiscretions should be kept quiet, and when we choose to disclose them, we’re usually doing it to absolve ourselves of guilt rather than to benefit our partner.

Listen to Mia Freedman’s recent interview with relationship psychologist Esther Perel. Post continues after audio…

So why does Jarvis feel it’s so important to catch people cheating? It’s clearly a question the private investigator has considered at length.

“When someone is doing the wrong thing, it’s generally not an isolated event,” he says.

“If someone has done something improper in the past, there’s a better than average chance they’re going to do something improper in the future. I would take the view that if someone is lying about their relationships, there’s a good prospect they’re lying about other things.

“I’ve dealt with many cases where a woman has been subject to a cheating partner, and it ends up being not just the infidelity – it ends up being a terrible separation. The husband may hide income, and so on.”

Jarvis says the majority of people who come to see him are women, and often, if cheating is uncovered, they’re left in a particularly challenging position “because of the treatment at the hands of their partner”.

Infidelity can be just the first in a chain of dishonest behaviour, including “hiding money… doing something they shouldn’t do with the children… not adhering to court orders”.

When it comes to how to tell whether your partner is cheating, Jarvis has just one piece of advice: trust your intuition. He says while it might be that “someone is not accountable, like they’re not answering their phone, or they are going missing at times where it’s expected that they should be somewhere, or staying later at work,” 99 per cent of the time, people come to him purely from a gut instinct.

“The innocent party will usually get a feeling that something is not quite right,” he says.

And that’s where his job – to collect evidence of infidelity – begins.

Lyonswood Private Investigators and Forensic Group have been taking part in cheating partner investigations for 35 years. 

Lyonswood is giving Australians the opportunity to put their investigative skills to the test by taking part in an online competition involving a case of infidelity. The first person to solve the case will enjoy one week of paid work experience learning the tips and tricks from one of the industry’s leaders in private investigations. To enter visit this site.