The popular Dirty John podcast follows the life of con artist and sociopath John Meehan. A few episodes in, and it’s easy to see how unwitting people seeking love online are at real risk of falling victim to a Dirty John.

“Victims aren’t actively looking to enter an abusive relationship; it just kind of mutates into one,” says Phillip Lenger, a licensed private investigator in Orlando, Florida who has dealt with many victims of mental, financial, emotional, and physical abuse. “If it sounds too good to be true, it probably is.”

Here are Lenger’s six key tips for identifying a possible Dirty John.

1: Being manipulated into a date.

Manipulators trying to score a date with a potential victim will use some of the following tactics:

Dares: I dare you to date me.

Bets: I bet you wouldn’t go on a date with me.

Guarantees: We’ll have a great time. I guarantee you’ll like me.

Options: Let’s go eat. If you don’t like it, you can leave.

“Wow, I guess all the signs were there,” is the common refrain from the clients who have hired Lenger to investigate deception or infidelity. But it’s hard to see the signs when you don’t want to see them.

2: When they pursue you…a little too much.

When you haven’t dated in a while, it can be thrilling to be pursued by a love interest. While there’s nothing wrong with pursuing your possible future spouse, things can very quickly take a scary turn.

“If you’re dating someone because they pursued you to the point where you were worn down enough to say yes, that’s not love, that’s obsession,” says Lenger.

3: Relationship Moving too quickly

A common online scam called “The Romance Scam” targets older men and women who have been single for a while. The scam begins as a virtual friendship, but quickly turns into a relationship – often within hours. The same scam can also occur offline.

Signs to watch out for include:

Saying I love you within days. Asking for a key to your home. Asking for financial information about you. Talking about marriage or moving in together. Wanting to meet family members within days of starting to date.

4: Changes in behavior and appearances

Manipulators tend to change their appearances, behaviors and even their beliefs. They’ll use excuses, lies and deception to present themselves as the person of your dreams. A sudden change to any of these things can be a very strong indication that they were faking their personality from the start.

Pay attention not only to your partner’s interests, but to their appearance. Are they showering more or less than usual? Are they suddenly afraid of you touching their personal belongings? Do they get mad at little things that didn’t offend them in the beginning?

5: Constant lies and inconsistencies.

This is a major one. The lies usually start small, with exaggerations about their accomplishments, their career goals or even sport successes. But they can quickly escalate, turning into a type of abuse where a manipulator will lie about your loved ones, isolating you from them and putting you at risk.

According to Lenger, your friends and family are the number one shield against an abusive relationship. Most manipulators need to pull you away from this “shield”, and will begin by lying about your loved ones’ motivations. When your family and friends raise concerns or try to protect you, a manipulator will claim that they’re attacking your relationship, or that they’re “jealous”.

6: They don’t contribute financially to the relationship

A difference in earning potential is normal. However, that doesn’t mean that the lower-earning partner can’t contribute to the relationship at all. Even if someone doesn’t have the financial means to pay their full share, they should be able to make up the difference in other ways.

“If you feel like you’re having to pay for time by giving them gifts, taking them out on dates, or even helping them financially, that’s not a relationship – it’s a financial agreement,” says Lenger.

How to avoid being manipulated by a Dirty John

Lenger says the most important thing is to listen to your gut, especially when something feels wrong. It’s also vital to stay in touch with your friends and family. They’re your number-one defense against manipulators.

His additional tips for staying safe include:

Don’t rush into a relationship. Take things slowly.

Protect your finances. That means no joint accounts .

Have a private investigator run a background check before things get serious.

Don’t “settle” – you can always do better.

If you follow your gut instinct, have a strong support network, protect your finances, and confirm that your partner is who they say they are, you’ll be less likely to fall victim to a Dirty John. If you think that you might already be in a relationship with a manipulator, talk to your friends or family, or contact a professional investigator like Phillip Lenger at TMS Investigations.com