Or some sort of bug had occured?
Well, i've just finished playing JA for the second time at hard level and when i have attacked sector 1, i founded (and killed) only 3 Santino's men...
1) YES! You have read well ! I wrote
3...
2) NO! I don't found a mistical teleport to Santino's Room (or something similar) nor i have act so quickly that Santino's men aren't able to respawn with their normal quickness 
3) In all the walktrought that i've founded, it is always said that Santino's men are unlimited in sector 1 and infact this happen to myself the first time that i've played JA (normal level) and the first time that i've played at Hard Level... until i'd managed to enter Santino's Room, each time that i kill a bad guy... another bad guy respawn, quit Santino's Home and engage my mercs.
Now... i'd killed 768 enemy in total, to this number it must add the enemy drowned during attack to sectors defended by mercs (combat resolved on tactical screen) or by guards (automatically resolved by computer). Infact enemy can even drown!! Generally when attaccking sector "not safely linked" and this number will never be take in count (Missing In Action?? :nuts
. Since the game is last for 61 days, with many attacks of this type, i can estimate that at least 20-30 enemy are drowned.
It's possible that the maximun numeber of Santino's Men is 800?? Someone other than me had managed to kill so many enemy or it's normal ?
P.S. : i've also tried to quick restore from day 60 and then i'd played until day 65... without doing nothing !! For 6 days no attack from Santino's Men !