Does killing all the guards trigger the alarm?

My friend and I were trying to stealth the Ukrainian job and we had it pretty well down. Usually there were two guards in the alley and one in the back rooms.

We killed the two in the alley, bagged and hid the bodies and sneaked into the room with the camera feed. Without fail, the crap hit the fan here. We would wait for the guard to come back into the room, hit him from behind and answer the pager.

While one guy did that, the other one dashed across the back and secured the manager's office. Somewhere in this sequence the alarm would get tripped for "suspicious activity" even though no civilian outside or in the front saw us.

In reading stealth guides for heists, I keep seeing people say to dominate one guard and kill the others.

If you kill all the guards does this trip the alarm?

Solution 1:

No, killing all the guards itself does not trigger the alarm, but you need to answer a pager every time you kill or subdue a guard. Your team can only answer four pagers successfully. The fifth pager will always fail causing an alarm. Most maps have more than four guards, but not all.

Also, in this particular case, it was probably a camera in one of the back rooms, which must have seen either the dead guard or the dashing to the manager's office.

Solution 2:

If a guard is killed during the stealth portion of a heist, then a player must answer his pager quickly or an alarm will be raised. If the player cancels interaction with a pager, or if too many pagers have already been answered – usually three without the Smooth Talker skill – then the operator will raise the alarm.

Source

Given you can answer ~3 pagers without Smooth Talker, if you kill more than 3 guards the alarm will go off automatically.