Final answer:
The concept described in the question is known as a 'modus operandi', which a serial killer may change over time to avoid detection. It encompasses all the planning and preparation stages a perpetrator undertakes before committing a crime. This can also be related to large-scale preparations for actions such as ethnic cleansing or genocide.
Step-by-step explanation:
The term you are looking for is often referred to as a modus operandi (MO), which is a Latin term meaning 'method of operation'. The modus operandi is the particular way or method a serial killer uses to commit a crime. It includes all the planning and preparation stages before the crime is committed.
Over time, a serial killer may change and perfect their modus operandi to avoid detection by law enforcement. This could include changing their target demographic, altering their method of killing, adjusting the location selection for their crimes, or varying the way they interact with potential victims.
Examples of preparation in broader criminal activities might include plans for ethnic cleansing or genocide. During this stage, perpetrators identify victims, create death lists, and use euphemisms like 'ethnic cleansing' to cloak their intentions. Part of the preparation might also involve building armies and indoctrinating the population against the targeted group, claiming a need for self-defense to justify their actions.