For a loss prevention officer to detain a person he/she suspects of shoplifting, they MUST have probable cause, usually visual confirmation of the crime. This ability to detain, the Shopkeepers Privilege, is found in Texas Civil Practice and Remedies Code §124.001 and provides:
A person who reasonably believes that another has stolen or is attempting to steal property is privileged to detain that person in a reasonable manner and for a reasonable time to investigate ownership of the property.
After huge losses, store management may pressure loss prevention officers to exercise Shopkeepers Privilege, but there are major risks if an officer becomes overzealous in its implementation: Civil Litigation.
To summarize, loss prevention officers must: