Caesar’s wife

Caesar's wife must be “above suspicion.”

Prov. The associates of public figures must not even be suspected of wrongdoing. (The ancient Roman Julius Caesar is supposed to have said this when asked why he divorced his wife, Pompeia. Because she was suspected of some wrongdoing, he could not associate with her anymore.)

Jill: I don't think the mayor is trustworthy; his brother was charged with embezzlement. Jane: But the charges were never proved. Jill: That doesn't matter. Caesar's wife must be above suspicion. When the newspapers reported the rumor that the lieutenant governor had failed to pay his taxes, the governor forced him to resign, saying, "Caesar's wife must be above suspicion."

Source:  http://idioms.thefreedictionary.com/Caesar's+wife+must+be+above+suspicion

In other words, “squeaky clean.”

This expression referred originally to Caesar's second wife Pompeia. According to rumours circulating in about 62BC, it seems that her name was linked with Publius Clodius, a notorious dissolute man of the time. Caesar did not believe such rumours but he made it clear, when divorcing her, that even Caesar's wife must be above suspicion. The expression like Caesar's wife also comes from this account, to refer to someone who is pure and honest in morals.  Source:  https://in.answers.yahoo.com/question/index?qid=20101207091032AAEGy7b

Or, we can come at it from this angle:  if you are above suspicion then you do nothing to make people think that you have acted wrongfully or improperly.  “While there is little evidence that the claims against him/her are true, all politicians need to be above suspicion.”  Source:  https://www.translegal.com/legal-english-dictionary/above-suspicion

Lets repeat those words from above - you do nothing to make people think that you have acted wrongfully or improperly.   We (TF) have added the “emphasis.”

So that’s about all we have to say on this topic of “above suspicion.”  When it comes to dealing with public matters, public finances, public anything; the top, number one, always most important criterion is – above suspicion.

The idea of explaining away one mysterious or suspicious act or expression or behaviour after another is not just wrong, the very need for it tells the public all they need to know about the involved person.  They are not up for the job.  They are not “above suspicion.”