Episodes 847-848 have been added to the Detective Conan Episode List.
It's been over 100 episodes since this the last time this plot thread was even mentioned, and nearly 200 since it had any focus at all (and more than a year since it came up in the manga as well, considering this arc was basically the most recent time), so chances are not low that you've forgotten about Chiba and Miike's arc entirely. So yeah, here's your biennial reminder.