It occurred  to me that there is a sort of difficulty in the Gemara  Ketuboth page 45 and Rambam אסורי ביאה chapter 3 halacha 8 of Forbidden Relations..   What I mean is this/ look at Deuteronomy  22 verse 13 and onwards. There you have the law about a girl 12-12,5 years old who is betrothed נערה מאורסה בתולה  that had sex with another man. This is the law that is known as מוציא שם רע. She is stoned.  Then comes the regular law [verse 22] about a married woman. If she had sex with another man, she is choked.  And then comes a law [verse 23] also about a נערה בתולה מאורסה girl 12-12.5 virgin who is betrothed. She also is stoned, but in the regular place of stoning, not at her father's house. 

Now just looking at the verses alone, you would say everything is simple. A girl had sex while betrothed and so she is stoned, If she  had sex after she got married, she is choked. But there is a special case that she had sex, and then got married --and her husband then brought witnesses and she is stoned at front of her father's house. Now off hand, it looks like the entire difference is when the sex was. If while betrothed, she is stoned. If after married, she is choked. But there is a special case where  it seems the sex was while betrothed, and then she got married, and then he husband brings witnesses, and she is stoned at her father's house even though she is now married. But furthermore --looking at the verses you can see that everything depends on when the sex was, not when the case is brought to court.

But since this is different from the regular case of sex while betrothed, so it is possible   that the sex here was after the chupa but before sex with her husband.

But in the Gemara and Tosphot and Rambam it is clear that sex after she got married, but before sex with her husband and then he brings witnesses, then she is stoned. Everything seems to depend on that the sex was before she had sex with her husband and he brought witnesses, They did not come on their own.

Still from the verses themselves, it looks like the sex was while she was betrothed. 

So even though i do not remember the gemara, still i recall that rava derived from somewhere כיוון דאישתני דינא אשתני קטלא  once her category has changed also her type of death has changed. so that if she had sex while betrothed and then married and then witnesses come she is choked. So from where ever rava derives this law, he has managed to show that there is at least one case where the sex was while she was betrothed and yet the type of death is by choking.  

And Rav Shach has a few paragraphs on that Rambam, so i might try to see what he says and if i can find any clarity about this.