Did Deb Kill El Sapo?

Back in the lab, Dexter figures out that Deb killed El Sapo. Magically, Debra shows up at the station to answer some of Quinn's questions.

Who does Deb kill?

Dexter rescued Debra and later killed Rudy "for the safety of (his) sister." In Season Four, Debra discovered the truth about Dexter's biological family. She was very upset and informed Dexter, thinking he had no idea of who his brother was, and went on to say that she loved Dexter more than anyone.

Does Saxton kill Deb?

He comes in and decides to let Saxon free, without questioning him, next to a bag of knives (has this guy not been watching the news?). So obviously Saxon kills him, grabs his gun, and shoots Debra in the gut before running away.