Detection

Detection is the rate of which a person is caught during a stealth portion in the heist. You can see your detection rating when you are in the loadout tab in-game. Your detection rate shows how fast you will be caught, and ranges from 3 to 75. The higher the detection risk, the faster a player is detected. All NPCs that detect the player detect them at the same rate, and detection is shared amongst the entire crew.

Guards
Guards range differently depending on where their location is at. If they are in a room required to have the lock picked, most likely those guards will not move from that spot. Outside or in large areas, guards usually patrol the area they reside in, and don't move to other places. Guards usually differ in clothing, and most have pagers, excluding the Thugs from Nightclub. When you are in a guard’s field of view, you have about a few seconds on your detection meter to get out of their sight (with 3 detection risk.) Failing to do so will result in them spotting you and attempting to call the police. Furthermore, given enough time, the guard will take out their unsilenced gun and fire at you, removing any way possible of a stealth heist without multiple people each with ECM jammers. However, you can kill them before they call the police, but most guards will have a pager that is required to answer. One can also hostage the guard using the Halt skill, which does not require them to answer a pager, however if on or above, a pager is required to answer when using Halt on a guard.

Guards can detect unsurpressed gunfire, loud sounds such as drills or explosions, masked heisters, hostaged Enforcers or civilians, broken glass, thrown bags, broken cameras, and dead bodies. Guards turn to look at a player that has dropped a bag, and consequently alerted, and guards that touch heisters, either in casing mode or masked mode get instantly alerted. They can also detect you if you enter restricted areas. Some camera operator guards will instantly get alerted when a keycard is used to disable the security, like in R&B Bank, and will quickly raise the alarm if not dealt with.

Shadow Raid warehouse guards have increased health compared to normal guards, and Authority soldiers have more health and wield a stronger weapon compared to weaker enemies.

Cameras
Cameras are a type of detector that is potentially risky if not dealt with. There are multiple ways of dealing with cameras. The first is breaking the camera, which is risky on most stealth heists, as guards will notice broken cameras and notify the police. On the difficulties of and above, all cameras on the map are Titan Cameras, meaning that they are unable to be broken. (Note that this does not affect Black Friday, Blood Money, and The Ozela Heist, as they either have camera based badges, side opportunities, or were deemed too difficult.) Another method of disabling the cameras would be looping them, using the skill Nimble basic. It is advised to spend the window of time wisely, as it only lasts 25 seconds. You can tell if a camera is looped by the static noise it's emitting. You can loop a camera as many times as you'd like, but you cannot loop an already looped camera. You can also place an ECM Jammer to disable them for the duration of the jammer. The last method would be disabling a camera room, either by killing a guard as seen in multiple heists, cutting a wire as seen in RO-Bank, putting in a keycard as seen in Brick Bank, or disabling a power box seen in Jewelry Shop.

Civilians
Civilians detect the heisters similar to guards but are unarmed. Unlike guards, they have less ways of detecting the presence of a robbery and will only react to loud noises, unsilenced gunfire, masked heisters, hostages, or dead bodies. Other items that alert guards, such as glass and bags, do not alarm civilians.

Pagers
Killing a guard will most likely have you to answer a pager soon after. Pagers appear a few seconds after killing a guard holding one, or halting them on +. If not answered, the police will be called due to suspicion. A heister can only successfully answer a pager four times. If attempting to answer a fifth time, the pager operator will get suspicious and call the police, ruining a stealth run. The 4 pager answers are shared over each heister, meaning that there is a maximum of 4 pagers answered over all the heisters. Pagers last for 8 seconds requiring a response and will flash rapidly for 4 more seconds before the alarm is raised. Having the ECM Specialist aced perk allows pagers to be delayed while the ECM(s) are still jamming, allowing some extra time to answer a lot of pagers or escape before the alarm sounded.