Where did the expression "give someone the third degree" come from?

the question has definitely been asked before.

Here is the answer:

Where did the expression about giving someone the third degree come from? - Jan, Denver

We've answered that before, but it's been awhile. The expression, which describes harsh questioning of a prisoner to elicit information or a confession, probably is related to the Freemasons, an international secret society. Achieving the third, or highest, degree of Freemasonry requires that the applicant pass grueling tests of proficiency. Since the 1890s, the third degree has been broadened to include any intense questioning, according to the Henry Holt Encyclopedia of Word and Phrase Origins.

You give someone the third degree when you tell that person strongly what is right and wrong and what they should and should not do. Example: "That judge really gave that guy the third degree, didn't she?"

When parents give children a serious lecture, telling them what they can and cannot do, they give them the third degree. Example: "When he get's home, I want you to give him the third degree."

People sometimes protest against being "given the third degree" when they are talked to and told what they should and should not do. Example: "Stop giving me the third degree."

http://www.goenglish.com/Idioms/Give+Someone+The+T...