Paterno, Gleason’s “best friend”.
By poisoning the cherry on top of the cake.
The sticky cards on the table.
Years ago, Paterno (born Yuri Patrenko) was planted in the C.I.A. He arranged to have a fellow K.G.B. mole as his examining physician. In this way, Paterno’s telltale vaccination scars and dental work went overlooked.
Though the cold war was over, Paterno still worked for Russia. Gleason, who had seen Paterno half naked on various beaches, was about to be briefed on the details of such marks and would have connected this information to his friend.
Paterno brought the cyanide, knowing that Gleason was famous for picking at food, especially desserts. When Paterno saw the candied cherry, he knew Gleason wouldn’t be able to resist. During his turn as dummy, Paterno filled the pitted fruit with several grains of poison, then replaced it on the marshmallow icing. Paterno’s hands were now sticky from the cherry and the icing, but there was no water to wash his fingers. He certainly couldn’t lick them. So, he wiped them off as best he could on a dish towel.
When Gleason filched the cherry during his last kitchen visit, he smoothed over the icing with his fingers, leaving no trace of the cherry, then licked his fingers clean.
During their last full hand, Paterno’s sticky hands gummed up the cards, leading Gleason to break out a new deck. Paterno was shuffling this new deck when Gleason collapsed. No one else had touched the deck and yet it also proved to be sticky, just like the old one.
The C.I.A quickly pieced together this scenario, causing Agent Paterno to quietly disappear from their list of active agents.