I'll nail you when I can finally prove who supplies you with cyanide. And then P.D. James would send Adam Daigliesh into finding another mystery killer who's a cop. I'd suggest her a title... I'd suggest 'Wole the Ripper!' Then Ms Cornwell would do an American adaptation of your story. She'd have no choice than to betray her Marino character by making him the mystery killer. But I guess she'd find difficulty in doing that because Marino isn't Black.