Who Poisoned the Victim? Meitantei Conan : Season 1 Episode 1006

Conan and Ran are at a party hosted by Kogoro's client, the second company president of Sasano Finance. The president was sent a death threat in the mail, and Kogoro has come to this party as his bodyguard. At the party are three guests, all of whom bear some grudge against the president. The threat is fulfilled and the president is poisoned. However...