He told BBC Radio 4's Today programme that it depends on a number of factors including:
- How the body has been buried
- What condition it was in when it entered the ground
- How expensive the coffin was
- Whether modern embalming techniques were used
He said: "I think it is certainly possible that they could find residual traces of radioactive material," but added it was doubtful they would find solid evidence of poisoning if only bones remain.
More top news
Harry and Meghan left Windsor Castle during Sunday afternoon after being hosted by the Queen and Duke of Edinburgh over the weekend.
Clare Waight Keller said it was an "enormous honour" to have been given one of fashion's most coveted jobs ahead of the royal wedding.
As temperatures rise over the coming few days, the risk of thunderstorms across some southern parts