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
A miniature Shetland pony has surprised its owner after unexpectedly giving birth to tiny 17-inch tall foal.
A six-year-old girl was bitten on the legs by a police dog while officers were chasing a suspect.
Taiwan has taken a new approach to covering the Labour leadership contest.