public void Die()
        {
            if (!IsDead())
            {
                return;
            }

            zombieAI.SetUpNavMeshAgent(false);
            zombieAI.enabled = false;

            if (KilledByKnife == true)
            {
                animator.SetBool("dieFromKnife", true);
            }
            else
            {
                animator.SetBool("Died", true);
            }

            GetComponent <AudioSource>().Stop();
            Destroy(gameObject, 5);
        }