"Horizon": How to Commit the Perfect Murder Season 43

The programme focuses on the notorious and as yet unsolved murder of Alexander Litvinenko. When ex-KGB spy Litvinenko was admitted to hospital in London, it took doctors several weeks to deduce just what was killing him – radiation poisoning. By the time they’d cracked it, he was dead. Litvinenko was poisoned somewhere in the capital by a man who had brought the deadly polonium-210 substance on a plane from Russia. The time it took doctors to diagnose Litvinenko gave the killer a window of opportunity to escape and he or she is yet to be found.
　　Interviewing a number of experts, the programme examines this and many other types of murder, from poisonings to staged accidental deaths. Forensic specialists lay down the facts and point out the pitfalls of trying to tamper with evidence. Then the experts go on to test a few fictional ideas, like could an icicle, melting away to leave no trace, be used as a weapon to kill someone?