Abstract: On June 26, 2009, Employee #1 reportedly bumped his knee on a piece of metal pipe after he slipped and fell into a shallow excavation while working at the Southern Regional Library, Los Angeles, CA which is located on the UCLA campus. There was no visible injury, and the incident was neither reported nor investigated by the employer at that time. The employee continued to work without incident until he left for vacation on July 2nd, 2009. On July 6, 2009, Employee #1 called in sick, was seen by a physician that evening, and was subsequently admitted to Holy Cross Hospital for a knee infection for which an abscess was surgically removed. Although the employer was aware of the employee's hospitalization, he had no information to relate the hospitalization to a work place injury until about July 13 when the employee was released from the hospital and informed his supervisor that the infection was related to the June 26, 2009 incident.