Here is the full list of all 9 Detective Grimoire achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Finish speaking to the Little Girl
Full suspicion on the culprit, none on anyone else
Complete the game
Get inside the tent
Complete the game 100%
Examine all the Boggy merchandise
Draw a cute ghost in your notebook
Read the letters on Remington's desk
Examine the crime scene