But apparently, there is a way around double jeopardy - here's the story of a triple murder and triple jeopardy:
Master Sgt. Timothy Hennis was convicted once before of killing Kathryn Eastburn and her daughters, Kara, 5, and Erin, 3. He even spent several years on death row awaiting execution after his 1986 conviction, but he gained his freedom after an appeal and acquittal at a second trial in 1989.
After that, he continued his career in the Army.
Years later, the move allowed prosecutors to put him on trial yet again -- and a U.S. Army court martial jury today unanimously found Hennis guilty of murdering Eastburn and her daughters nearly 25 years ago.
Hennis was found guilty and has now been sentenced to death for the second time.
Link (Photo: Jim R. Bounds/AP)