We had a local criminal trial the mother of a dead young girl. She and her husband were both accused of drugging the girl, beating her to death and then throwing her body into a river. Police divers recovered a plastic garbage bag and several strips of duct tape, but not the girl's body.
During the mother's trial, the lack of a body became a major issue for both sides. Prosecutors had to use personal testimony from the husband to suggest the murder happened the way they claimed. He verified the use of a garbage bag and duct tape, for instance. Tests on the recovered items showed traces of human DNA.
The defense argued that if there was no body presented as evidence, then any number of things could have happened. The crime never actually took place, or the girl could still be alive somewhere. Even though the circumstantial evidence was strong, the lack of direct evidence kept reasonable doubt in play. The jury actually acquitted the mother.