Not sure what the FBI was being issued in '92. For a patrol officer it would have most likely been a Streamlight SL-20X or Mag-Lite Magcharger if they kept up with the times. As far as police-style lights in production then, off the top of my head:
-The Surefire 6/6P/6R and I presume 9P would have been available. Someone with more SF info could say if some of their other models like the 8X or 6Z were around that early.
-I believe ASP had the Triad going by then but someone correct me if I'm wrong. That was a lithium xenon light along the lines of the SF 6P.
-Streamlight at the time was making the SL-15X/20X/35X for rechargeable duty lights, plus the models remaining from their D/C-cell adventures in the 1980s, and at least the Streamlight Jr AA pocket light. They were a couple years away from introducing the Stinger at this point. I'm not counting their flashlights for other markets like the Litebox and Survivor.
-Mag-Lite had their full line of incandescent products that people today would recognize. Their lineup didn't really change at all until the mid 2000s.
-Legend (later Brinkmann Legend) would have been in production. These were incandescent lights similar in basic operation to Mag-Lites.
-Brinkmann had one or two police-style D-cell lights of their own, like the 5-3-2. Not sure how much luck they were having actually marketing to law enforcement. They also had a few AA/AAA pocket lights that were modified versions of their original Mini Mag-Lite clone.
-GT Price made an AA pocket flashlight (Code 4 Jr.) that looked like a Mini-Mag but with a clickie side button. I think their full size light had turned into a Brinkmann property by then.
what other lights may have seen use in the field prior to the high-pressure xenon/halogen incandescent revolution of the late eighties? Reference photos would be appreciated.
There was a whole constellation of aluminum D/C-cell police flashlight brands that disappeared in the mid '80s. The industry started with the Kel-Lite in 1968. The other main players that followed were Pro-Light/B-Lite, LA Screw family, Streamlight, and later Mag-Lite, plus a few smaller brands that didn't get as much traction. Mag-Lite and Streamlight came out as the top dogs and everyone else died or went into "oh they still sell these?" levels of production by 1985.
Anything specific you want a photo of?