The last year the model LE6920 was marked with LE restricted markings with "Colt's Law Enforcement Carbine" markings was in 2010.
By 2011 the factory changed the roll markings and model to SP6920 and new marked "Sporter M4 Carbine", no caliber and no LE restricted markings (I have this one too).
In the next year 2012 the markings got changed again to "M4 Carbine" with CAL. 5.556 MM, still no LE restricted markings (I had this one but I gave it to my son).
The last 100 production units they sold with factory papers authenticating they were made as the last 100 units with the LE restricted markings, not sure exactly when but probably between around 2011 to 2013.
At the very end of 2013 the factory released some remaining 105 units with LE restricted markings without factory paperwork, the serial numbers range from LE 95XXX to 96XXX, but those were snapped up by most people in the industry and gun collectors.
Don't pay too much premium for them just take your time and buy the lowest price you can find, there is no panic buying time now during Trump's administration, so the prices should go downward.