"We saw him in a small storage room on the ground floor".

The vestibule:

Mr Oswald told Captain Fritz
-----------he visited the 2nd fl lunchroom
before the parade
-----------he went outside to watch the parade
-----------he had an exchange with a police officer in the vestibule (front entrance, first floor) just after the shooting
Mr Ochus Campbell told reporters 11/22
-----------Mr Oswald was spotted in a small storage room on the ground floor shortly after the shooting
(Note: There is a small storage room just off the..... vestibule.)
DPD told reporters 11/22
-----------Mr Oswald had an exchange with a police officer at the front entrance just after the shooting.
The details of what really happened may still be a little hazy, but one thing is clear:
All the action was at the front entrance, first floor. 