I just did an FCC proximity license search on the South Bay Galleria mall, and found
WQOK239. Try:
463.3625
463.5625
463.6625
One (or all) of those should be mall security, utilizing a repeater (FB2 type in the license). Be sure to submit to the database if you identify the users and PL/DPL tones.
Considering Redondo Beach PD is also in the 460 MHz range I would guess they have mall security programmed in their radios for interop purposes.