Muistikirja. This is more like a notebook where you make notes of something, like what a detective might use.A notebook in school: vihko.
侦探Zhēntàn
Genre might be a big word, but there are fantasy detective books (the Thursday Next series by Jasper Fforde, for instance).
Criminal Justice. That might get you to where you want to go.
we are police to meet you
I think it might be The Woman in White by Wilkie Collins.
get followed by bad people might get killed
detective actor dancer musician
A detective's personal qualities should include good people skills. Much of a detective's job is done by talking to people and asking questions. A detective might also have to function on very little sleep.
You might find them at gungrip.com
It might have been The Pink Panther because he starred in a film of that name and there was a film in the 1960s also called The Pink Panther and that was about an inept Parisien detective.
Switzerland speaks German, French, Italian and Romansh. Germans might say 'Hallo". French might say Bonjour. Italians might say Ciao.