If you lost something, go directly to a security personnel at the place. Ask for the office location where everything is held. Do not just call or rely on somebody saying it is not here etc. Also, institutions do not divulge info over the phone for security to benefit the true owner. Any manager of the place may know of your item but managers or supervisors may be plenty and even gone for the day. It best to confirm and account with all if turnover has been made then leave your contact number. Hope this helps.
That's a good place to start. Or the Convention Center office.
The convention centers security office
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