Professor Dumbledore collected Hokey's memory of Tom Riddle for his Pensieve. In the memory Hokey helps her mistress, Hepzibah Smith, prepare for a visit from Tom. Hokey serves tea and cakes to the pair, and is ordered to bring Hepzibah's two finest treasures to the room to show their guest. Once Hepzibah has finished showing Tom Helga Hufflepuff's cup and Salazar Slytherin's locket, Hokey removes them from the room.
Hokey was convicted of the murder of her mistress, who died two days after the visit from Tom Riddle. She was found guilty of poisoning Hepzibah's evening cocoa by accident, with a lethal and little-known poison. It was concluded that the old and confused house-elf used the poison instead of sugar, as she remembered putting something into the drink. Dumbledore believes that Hokey's memory was modified to include this element by Tom Riddle, who was the true murderer.