Usage of the idiom you cant squeeze blood out of a turnip

Does the idiom you cant squeeze blood out of a turnip only refer to money or financial-related situation? Or could it be used for any other instances i.e. evidence. For example, would it be correct to use the idiom in the context of the sentence below?

The prosecution examined the victim thoroughly in court, but failed to get any implicating evidence against the accused. It is like squeezing blood out of a turnip

The phrase simply means that you cannot force from something that which is not there. Despite the anger and malevolent forces that you apply to the turnip, or other largely innocent vegetable, it will not come across with the goods.

There is a corollary to the phrase, "You can't squeeze blood from a turnip." which is known as [somebody's] Satisfaction; reference on the way. Insert your own name or that of a famous lawyer. "No, but you can stomp the sh*! out of it."