Also found in: Wikipedia.
Not suspected of any wrongdoing or crime. Because everyone thought he was such a good citizen, he remained above suspicion after the robbery.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
[for one] to be honest enough that no one would suspect one; in a position where one could not be suspected. (This is a translation of words attributed to Julius Caesar, who divorced his wife, Pompeia, on the grounds of her possible involvement in a public scandal; Caesar stated, "Caesar's wife must be above suspicion.") (*Typically: be ~; keep oneself ~; remain ~.) The general is a fine old man, completely above suspicion.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
So trustworthy as never to be suspected of wrongdoing, as in "The wife of Caesar must be above suspicion" (Charles Merivale, A History of the Romans under the Empire, 1850). The phrase was given further currency when it was used for the title of a very popular World War II spy film starring Joan Crawford ( Above Suspicion, 1943). A similar idiom using above in the sense of "beyond" is above the law, usually describing an individual or business behaving as though exempt from rules or laws that apply to others.
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.