Mario Scaramella first claimed to have been hit with five times the lethal dose of polonium 210, the radioactive substance that killed the former Russian spy Alexander V. Litvinenko. “I’m not in the best mood,” he said in an interview with Italian television from his hospital bed in London last month. Then two days ago, he walked out of the hospital with minute traces of radioactive poisoning but was otherwise perfectly fine. It seemed a classic performance for Mr. Scaramella, 36, who has emerged as the oddest footnote in the mystery of Mr. Litvinenko’s death. Full Story