What is a common method used by private investigators to gather evidence?

Surveillance and observation are fundamental techniques employed by private investigators to gather evidence. This method involves closely monitoring a subject's movements and actions to collect pertinent information, often without the subject's knowledge. It is a discreet and effective way to obtain insights into a person’s behavior, whereabouts, and activities relevant to a case.

This approach is considered lawful when conducted within the boundaries of the law, allowing the investigator to build a comprehensive understanding of the situation. The evidence collected through surveillance can play a crucial role in various investigations, including infidelity cases, insurance fraud, and more.

The other methods presented, such as unlawful search of private property, aggressive interviewing, and the use of bodily force, are not only unethical but also violate legal standards. Unlawful searches can result in excluded evidence and potential legal repercussions for the investigator. Aggressive interrogation techniques can lead to unreliable information and may infringe on individuals' rights. The use of force is illegal and contrary to the professional ethics expected of private investigators.