Comma placement when joining two independent clauses with a dependent clause and the word, "and."

I'm having a problem finding an example of comma placement when two independent clauses are joined by a dependent clause and the word "and". Does the comma go before or after the "and"?

For example:

Mary asked John for the third time and, without blinking at eye, he finally turned down the stereo. (I've placed the comma after the "and")

Here's another example:

John ignored Mary throughout the entire meal, and letting out a heavy sigh, she stood up and left the room. (I placed the comma before the "and")

Which is correct?