Forensic engineering is the investigation of materials, products, structures or components that fail or do not operate/function as intended. A criminal aspect is possible in any investigation but is not always the case, generally the purpose of a forensic engineering investigation is to locate reason or reasons of failure with a view to improve performance or life of a component.
Most manufacturing models will have a forensic component that monitors early failures to improve quality or efficiencies.
Insurance companies use forensic engineers to prove liability or alternatively non liability.
Most engineering disasters (building collapses, out of design anomalies) are subject to forensic investigation by engineers experienced in forensic methods of investigation.
Train derailments, aircraft crashes and some automobile accidents are investigated by forensic engineers particularly where component failure is suspected.