Private Detective
Private Investigator, Detective, Sleuth, Investigator
noun, verbal noun, の adjective
You look for things and you spy on people. Your job isn't as glamorous as it sounds. You're a private detective.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
彼女は結局探偵になりました。
She ended up becoming a private detective.