I have a pretty hard question to answer... I say it in advance, I am not going to kill anyone or even poison someone. I am telling you that, because I tried to ask this on another forum and they accused me of a murder commitment... The following question is stated in an assignment made by a university in our country for high school students. So it's a competition, actually, which is supposed to be done at home.
I've been trying to solve this for so long, but without a result... So, let's get to the question. Which INORGANIC compound injected into his instep could have killed the man, who was found dead? Details: that compound can be commonly found in the human blood, but just in low concentrations. The man was killed by an injection into his instep and the investigator found out that it was a successful suicide attempt. But the poisoning cannot be clearly proclaimed, because this compounds concentration increases by decomposing of human cells after death. And the last thing I've got written here - the poisoning causes quick and very painful death... Please can you help me identify this compound and also tell me the reason why it was injected by the victim into his instep... Thank you very much.