That is a famous case because the perpetrator believed that he could not be found guilty because there was no corpus delecti - he believed that this latin tag meant 'if there is no body then there is no way to be convicted of murder'.
But of course corpus delecti means 'the material evidence of a crime'. The dissolved remains of the acid-bath victim were enough to prove that someone had been dissolved in acid, and so the acid-bath murderer was put away.
The reason I brought up that case is to show that the State may never be able to establish the exact cause of death yet may still prove murder. Otherwise, all a murderer would need to do would be what the British murderer did.
That's the body.
It may be in solution, but it's still a body.