Damage mod.  Another of those "hasn't played for a year, returns to hackusations" cases.

He emptied a server as people cried "hax" at him.  Check this battlereport: http://battlelog.battlefield.com/bf4/battlereport/show/1/889762981936516096/846247489/

16 kills, all with Scar-H.  No HS ribbons so no more than 2 HS out of the 16.  That means 14 kills with chest/tummy/limb shots and at most 2 kills as headshots.  So that'd be 14 kills at 33 damage (at most) and 2 kills at 33*2.13 damage (at most).  (14*33 + 2*33*2.13)/16 = 37.7 damage per shot is the very most he could pull off.  He killed 16 people with 32 hits, for 50 damage per shot.

http://battlelog.battlefield.com/bf4/battlereport/show/1/889769905268608000/846247489/  34% kills/hit, no head shot ribbon.

http://battlelog.battlefield.com/bf4/battlereport/show/1/889713973054665856/846247489/ 37% kills/hit, one HS ribbon

I wouldn't normally ban someone for a single game with 16 kills where the DMG value is too high--statistical anomolies happen--but with his other high DMG battlreports and the 428 days of idle followed by returning to play with unlikely stats, I'm convinced.