A more thorough explanation:

Definition: Non est is a Latin term that means "he is not found." In legal terms, it refers to a statement in a sheriff's return indicating that the person ordered arrested could not be found in the sheriff's jurisdiction. It is sometimes shortened to non est and abbreviated as n.e.i.

Example: If a sheriff is ordered to arrest someone who has committed a crime, but that person cannot be found in the area under the sheriff's jurisdiction, the sheriff may file a return stating "non est inventus," meaning the person was not found.

Explanation: This example illustrates how non est is used in legal proceedings. If someone is not found in the jurisdiction of the sheriff, they cannot be arrested or brought to trial. The statement of non est inventus indicates that the person is not present and cannot be held accountable for their actions in that jurisdiction.