After a helicopter crash in 1999, which resulted in the deaths of six Marines and one sailor, the United States Navy performed an assessment of their equipment and decided, among other things, that they needed a new search and rescue knife. The KA-BAR knives issued to the SBUs (Special Boat Units) had catastrophically failed to cut the Marines free from their webbing.
The Navy went to Emerson Knives, Inc., where the owner, Ernest Emerson, designed and fabricated a working prototype within 24 hours. The Navy found that the knife met their needs, and the model was dubbed the "SARK" (Search and Rescue Knife). The SARK is a folding knife with a wharncliffe-style blade and a blunt tip designed so a rescuer could cut trapped victims free without stabbing them. Seeing another need in the police community, Senior Corporal Darryl Bolke, a police officer of the Ontario Police Department, approached Emerson and asked for a modification to the SARK. Bolke's request was to make the tip of the blade pointed rather than blunt. Emerson replaced the blunt end of the SARK with a pointed end and named it the "P-SARK", or Police Search And Rescue Knife. Bolke wrote the knife policy for his department, the first of its kind in the United States. The P-SARK has been adopted by a number of law enforcement agencies since that time.
In 2005, the Navy changed the requirements on the SARK to incorporate a guthook on the back of the blade for use as a line-cutter. Emerson made the change on this model, which was designated the NSAR (Navy Search And Rescue) Knife and only made available to the United States Navy.