After completed all 3 tasks, talk to the coworker at the counter.
He will say that there are no shift worker. Then go to the staff break room.

Check the pink note in the locker where the post-it is attached.
Talk to the coworker at the counter again. and He will said he told the manager about this.

Now enter the manager's office, she is away.
and You can take the elevator.

Pick up the manager's hand next to the dead body and touch it on the door lock.
Check the trail of fingerprints and enter the password.

Pick up the barcode scanner right next to the entrance.
Find other coworker and talk to him.

Step on each pattern on the floor.
and Find a pattern that heart beating sound with a white border.
When you find it, go straight in the direction of the red arrow.

After repeating it several times, the screen is distorting and the heart beating sound goes louder and faster.
Scan the barcode scanner to the hanger that makes the loudest heart beating sound.
Continue clicking and you can go to the next section.

I wasted over two hours in the hanger section :(
I hope you don't waste your time like me!