"Manipulators are often quite skilled in the various ways to deceive, con, and otherwise lie. One of the most subtle but yet effective ways to lie is lying by omission. A very skilled manipulator might even recite a litany of very true facts but then (possibly unbeknownst to you) deliberately leave out a key detail that would shed an entirely new light on the reality of a situation. All of this is done for the purposes of impression management and outcome manipulation."

Example of Lying by Omission 

"An incarcerated female criminal offender put in an “emergency” request to see the consulting physician. 

She told him that she had been treated for “anxiety” and “depression” in the free world but that no anti-anxiety or antidepressant medication had been prescribed for her since arriving at the prison (true fact).  

She rattled off the names of several persons she knew who had been prescribed medicine, whereas she had not (again, true facts). She stated that was being discriminated against because she had filed an official grievance (it was factual that she had filed a grievance). 

She painted a picture of a hurting, unfairly treated person with a serious condition who only wanted help but was denied. She was the victim, the “corrupt system” was the victimizer (playing the victim role is an effective tactic in itself). The consulting physician was unfamiliar with treating individuals with severe disturbances of character. 

When the physician consulted with the rest of the staff, she was leaning toward prescribing medication to this inmate. He then learned what the inmate “left out” of the story. She had been to many clinics (i.e. “doctor-shopping”) in the free world and along the way managed to score many different diagnoses and abusable drugs until the medical community in and around her town became aware of her game. 

She didn’t say that she had been given two independent and complete psychiatric evaluations, with both psychiatrists deeming she had no true mental illness (unusually, she even had no chemical addiction issues of her own - her criminal ”business” was dealing in abusable prescription drugs) but was merely trying to secure drugs she could sell even in prison. 

In fact, she had been caught selling drugs she entered the prison with and that was one of the many reasons she was screened so carefully with regard to any possible real need for them. 

It was also no accident that this inmate put in her “emergency” request on a day that she found out that a consulting physician who had never consulted to the prison before would be on duty."

"Sorry, can you help me understand the whole picture here? I feel I'm missing out on something..." 

This is a great way of NOT accusing them directly to avoid them being defensive. And at the same time you can observe how they react to it. Whether they quickly dismiss your request or divert the topic on other things (signs of guilt). Or are they interested in helping you out better understand things. 

People will tend to distance themselves from lies by referring to themselves less when they're telling them.

The liar may use fewer personal pronouns like: "me, I, myself, and mine". So if someone were to lie to you that the home-knitted trousers you made them for Christmas are just the ticket, they might say something like: "Yes, they're lovely. How did you find time to make them? They'll be very useful for impressing people at important social events!" Notice that they didn't refer to themselves at all here.

Someone who genuinely likes your arty-crafty gift might say: "I really love them. I can't wait to wear them tonight at the charity ball! They really suit me." Here, the person associates themselves much more with what they are saying and also uses emotional words to express their connection to what they're telling you.

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