The most effective way to ensure that a newly formed internal audit activity remains free from undue management influence is to establish the internal audit activity's position within the organization through an audit charter. According to the Institute of Internal Auditors (IIA) standards, the audit charter should define the purpose, authority, and responsibility of the internal audit activity, clearly outlining the scope of internal auditing within the organization. This foundational document formalizes the internal audit function's role and provides a framework that supports its operational independence.
The Institute of Internal Auditors (IIA) - International Standards for the Professional Practice of Internal Auditing.

The installation of surveillance cameras over a door that provides entry to an area with hazardous materials, and a high risk of explosion, represents a preventive control. This control aims to deter unauthorized access and potential mishandling or sabotage, which could lead to dangerous incidents.
The IIA's guidance on different types of controls including preventive, detective, and corrective controls.

According to IIA guidance, the chief audit executive (CAE) must obtain competent advice and assistance if the internal audit activity lacks the knowledge, skills, or other competencies needed to complete the audit engagement. This ensures that the internal audit activity can effectively carry out its responsibilities by supplementing its capabilities where necessary to maintain quality and effectiveness.
IIA Standard 1210 - Proficiency

The use of judgment in designing, implementing, and conducting internal control is essential and enhances management's ability to tailor controls to the organization's unique circumstances, thereby making better decisions. However, it cannot guarantee perfect outcomes as it involves estimating and forecasting future conditions, which are inherently uncertain.
COSO Internal Control Framework

The internal audit activity can be considered a type of governance control. Governance controls are those that are designed to ensure that the overall direction, administration, and control of an organization are maintained.
The internal audit provides assurance on the effectiveness of governance, risk management, and internal controls.
The IIA's guidance on the role of internal auditing in enterprise-wide risk management.