This tutorial explains how to implement a search behavior around the last seen position using behavior trees.
Unreal Engine 5 AI - Search last Seen Location.
When player or any of the opponent character identified by an AI NPC character, the character will start moving towards the identified enemy and engage in combat. But, if player manage to break the line of sight, AI character should search the last seen location and if the plyer is not found, sheath weapons and return to regular duties.
Additionally, if you want to visualize the last seen position as a silhouette or a snapshot of the character mesh, this tutorial explains the process.
