Now, when you heard "switch to North" did a police officer say that or the dispatcher? If it was an officer then perhaps bellmawr has their own frequency that is not monitored by county. If not then its probably something we dont have here on the database. Maybe if you hear that again try doing a frequency search in the 500 Mhz range and see if you come up with anything. I guess its worth a shot. I'd try it here, but I barely get either zone 1 or 5, so I doubt if I'd be able to get their switchover.
My list of frequencies for Camden county has a channel called "North siwtch over". I can't remember the frequency at the moment, I'll post it up when I get home. As you probably know camden county has many small towns and they do use other local channels that central doesn't have.
Last time I checked, Bellmawr PD used 507.3625 PL 192.8 simplex as their switchover channel. This freq was licensed to the Boro but it appears that it expired. However if County did say "switch to North" then the above freq that Skypilot posted is correct.