The Security Department is SCI-Pathos' main armed combative department, responsible for protecting the Foundation's assets and ensuring the safety of its civil personnel. Security personnel are tasked with guarding various key locations in Site Phi while also maintaining control over the facility's Class-D population in Site Omicron. As the facility's main security force, they are also responsible for ensuring that civil departments are able to carry out their duties unimpeded by misbehaving Class-Ds, rogue personnel, and hostile forces. This includes but is not limited to escorting events hosted by civil personnel, responding to Class-D riots and escapees, fighting off hostile forces during raids conducted by Groups of Interest, and securing anomalous items studied by the Scientific Department. Members of the Security Department can expect to work alongside members of the Mobile Task Forces—Pathos' smaller and more specialized combative force—to reach these ends. 

The bulk of the department consists of unspecialized Security personnel referred to as "Base SD". These members are the backbone of the Security Department's presence and are typically tasked with the department's less difficult and lower-risk duties. The department also contains subdivisions that are equipped to handle the duties that require advanced training, knowledge, and/or equipment that Base SD members do not have access to. These subdivisions include the Combat Support Unit (CSU), the Military Police (MP), and the Security Response Unit (SRU). Each subdivision has its own requirements and entry process which are tailored to the duties their members will be expected to fulfill. Security personnel can also gain access to more duties and equipment by climbing the ranks, with each rank playing its role in the department's hierarchy and opening up new duties for members to carry out. 

More information regarding specific duties, rank requirements, and more can be found in the Security Guidebook, which lays out the guidelines that all members of the Security Department must follow and contains everything a prospective member would need to know about how the department functions.

Application entry. Subdivisional entry method varies.