The first problem was positively identifying the source of the transmissions. I was hearing them on the same channel as a local GMRS repeater I use. I heard references to cleaning, food court etc. With all of the local strip malls, hotels and more within a few miles, many using FRS radios I couldn't ID them. Then one day I heard a reference to a hand cleaning station, then a few seconds later I heard the mall security on the same frequency then on their own frequency. That nailed it. I had the call sign for the mall security frequency.
Next stop was the FCC database. I looked up the call sign for the mall's security. Got the FRN number. I was lucky the mall security frequency was registered to the mall and not the mall security company, which is an outside service. Then did a search for ALL licenses under that FRN for the mall.
0002748242
https://en.wikipedia.org/wiki/Lakeside_Mall
I guessed the house cleaning would be registered to the mall. Bingo, there it was.
KAB1523
https://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=194751
Under the "Admin" tab scroll down to the section "Special Conditions". The exact frequencies are listed there, the pair for the GMRS repeater channel 16, which is where I heard them.