What would you do if you lost the ability to sleep? (Short story written and cover art by me!)

You are the detective solving a murder case, can you figure out the perpetrator of the crime? As usual cover art by me!

Prompt I got last year to write about for a story in class! It's pretty short and has similar tone to the story lamb to the slaughter. Since that's why I did the assignment. The characters and stuff I made up though, hope you enjoy! The prompt was, write "the perfect murder" Cover also drawn by me