To prove a defendant was negligent in hiring, supervising, or retaining an employee in California the plaintiff must show that: 1) The employee was unfit or incompetent to perform the work for which he or she was hired; 2) The defendant knew or should have known that the employee was unfit or incompetent and that it created a particular risk of harm to others; 3) The employee's unfitness or incompetence caused you harm; and 4) The defendant's negligence in hiring, supervising, or retaining the employee was a substantial factor in causing your harm.