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.
Complete the game
Complete the game 100%
Get inside the tent
Draw a cute ghost in your notebook
Finish speaking to the Little Girl
Full suspicion on the culprit, none on anyone else
Read the letters on Remington's desk
Examine all the Boggy merchandise
Examine the crime scene