I'm wondering if there is an idiom, phrase, expression or other figure of speech that would replace the following:

"People who are innocent, don't ever act guilty (therefore you must be hiding something)" Or "Guilty people are more likely to get nervous"

For example, this might be said by a policeman when searching somebody and they are acting suspicious. Another example might be if your significant other is acting suspiciously and think they might be cheating. The basic message is that somebody is getting bad signals from someone else and they will try to find out what they are hiding. Not sure if this is gonna make much sense to anybody. I'm really not sure if something like this exists but let me know if you have any ideas!


9 Answers 9


where there's smoke there's fire

Merriam-Webster describes this as:

used to say that if people are saying that someone has done something wrong there is usually a good reason for what they are saying

  • 7
    I know it in the form There's no smoke without fire.
    – Colin Fine
    Commented May 9, 2020 at 8:08
  • 1
    @ColinFine perhaps that's the British English version, I've only heard "where there's smoke, there's fire" in the US.
    – Kevin
    Commented May 9, 2020 at 21:17
  • I've heard both, but my answer is more common in America AFAIK.
    – Barmar
    Commented May 9, 2020 at 23:50
  • Actually, now I think about it, I am familiar with both forms.
    – Colin Fine
    Commented May 10, 2020 at 0:46

"If it walks like a duck, it quacks like a duck, it's probably a duck."

Duck test


The following proverb may express the idea you are trying to convey:

A guilty conscience needs no accuser:

Prov. If you have done something wrong and feel guilty about it, you will be uncomfortable and want to confess even if no one accuses you of wrongdoing.

  • Even though no one noticed him eating most of the cookies, Peter felt so bad about it that he told us what he had done. A guilty conscience needs no accuser.

(McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.)


Here’s a po­etic proverb from Solomon’s com­pi­la­tion, older than the English lan­guage to be sure, but trans­lated id­iomat­i­cally enough to English in the NIV edi­tion of the Bi­ble:

¹ The wicked flee though no one pursues,
     but the righteous are as bold as a lion.

Proverbs 28:1

I don’t know off-hand of an ex­am­ple in print out­side of the Bi­ble (if I find one I’ll up­date), and the only one a quick Google search re­vealed was be­hind a pay­wall at content.time.com, so it’s not a com­mon id­iom across the English uni­verse, but I’ve heard the first half, “The wicked flee when no one pur­sues,” used by it­self when a po­ten­tial sus­pect starts ex­plain­ing his al­ibi be­fore he’s even been asked.

Edgar Al­lan Poe wrote a hor­ri­ble story, The Tell-tale Heart, which de­serves men­tion here be­cause of its graphic il­lus­tra­tion of this proverb. In the last sen­tence of this story, the per­pe­tra­tor of a mur­der is moved by his guilty mad­ness to con­fess to the in­ves­ti­gat­ing offi­cers, who un­til then had no ev­i­dence against him:

“Vil­lains!” I shrieked, “dis­sem­ble no more! I ad­mit the deed! — tear up the planks! — here, here! it is the beat­ing of his hideous heart!”


If the suspected person is more speaking guiltily than acting guiltily, and depending on the education and current mood of the person noticing this (and the situation in which they would be saying it), the modernized Hamlet/Shakespeare quote "methinks the lady doth protest too much" can be used.

This does not answer the asked question directly - a phrase for a general statement about behavior of the guilty vs innocent - but it's something an observer or interrogator might say to indicate their thoughts about someone's guilt, as judged from the denials.

A person could say this out loud to the "suspect" to indicate they don't believe their innocence or their denials, or they could say it to their partner where the "suspect" would not hear it (and in this usage, it could be somewhat humorous because of the archaic reference), or they could say it just to themselves.


Guilt is written all over your face

This idiom means that the guilty person cannot hide their guilt, and perhaps the more they try, the more obvious it becomes.

The Cambridge Dictionary has it:

written all over sb's face
If an emotion is written all over someone's face, it is clear what they are feeling:
Guilt was written all over her face.

Merriam-Webster has it too:

written all over someone's face
showing or evident by a person's expression
Her guilt was written all over her face.


Gnawing conscience

Guilty conscience that keeps bothering you; a sense of guilt that keeps eating away at you. Example - “I know what I did to my first wife was wrong and it has been gnawing at my conscience for all these years.”


  • 1
    I want to throw in here that, as common as such sayings are, this simply is NOT TRUE! Quite commonly a person may "act guilty" (whatever that means) because, while they did not commit the act, they are afraid of being accused of it. Or they might be acting guilty because they are actually guilty of some other (quite venial) act and are afraid it will be discovered.
    – user247327
    Commented May 9, 2020 at 16:55
  • Experienced police officers know that a certain percentage of innocent, honest people get very nervous when being questioned, even when they have done nothing wrong. Commented May 9, 2020 at 20:50
  • They also know that many career offenders are experienced at being glib and plausible. Commented May 9, 2020 at 22:38
  • 1
    Experienced police officers know that a suspect who is nervous under interrogation can often be made to confess, and later be convicted; I suspect that many such officers leave it at that, and don't care about actual guilt or innocence.
    – Beta
    Commented May 9, 2020 at 23:39
  • I work in the UK justice system; I meet police officers every day, and I have to say that I don't like them. I am always guarded with them. Commented May 9, 2020 at 23:40

"The lady doth protest too much, methinks" - William Shakespeare Hamlet


My mom used to say it to me when I was guilty.


If the shoe fits (US)

—used to say that something said or suggested about a person is true and that the person should accept it as true

  • "Are you calling me a cheater?" "Well, if the shoe fits, wear it."


If the cap fits (British)

—used to say that something said about a person is true and the person should accept it as true

  • They may not like being called careless, but if the cap fits, wear it.


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