I haven't been in the Detroit area, but try a few of these and let
us know what you hear.
 
FBI first:  These days, most of their repeaters are in the 167 MHz
range with 163 MHz being used for inputs and simplex comms.  Check
also the 162, 168, 170 and 173 MHz ranges.  
 
ATF:  nationwide, they operate on 165.2875.  
 
DEA:  try 417.750, 418.950, 418.750, 418.675, 418.825, 418.900, 
418.975.
 
I'd think US Customs would be active on 165.2375.
 
Also, US Border Patrol may be heard on 163.625, 163.675, 162.825 to
162.975, 163.650, 163.725.
 
US Marshals use 163.200 nationwide.
 
Try the US Secret Service on 165.375, 166.4625, 166.2125, 165.7875.
 
Remember that FBI, Customs, Secret Service and DEA use DES digital
voice encoding/encryption, so hearing a lot of hiss is normal.
Monitor these frequencies anyway; you never know when comms will
be in the clear.
 
This is just a very small sampling of active federal frequencies.  Long
time contributor Roger Cravens periodically posts outstanding lists
in here.  Keep your eyes open for his postings; he's long overdue.
Until then, search 162.000 - 174.000 MHz and 400 - 420 MHz for active
frequencies.  Good luck!
--- Maximus 2.02
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