Season 12 Jul 1964 – 6 Aug 1964 · 6 episodes1The Jockey Cap Case - 19272 Jul 19642The Trick That Failed - 19189 Jul 19643The Green Bicycle Case - 191916 Jul 19644The Teenage Murderer - 192623 Jul 19645The Whistling Corpse - 192730 Jul 19646The Perfect Crime - 19346 Aug 1964