The motion of a second class particle for the tasep starting from a decreasing shock profile

We prove a strong law of large numbers for the location of the second class particle in a totally asymmetric exclusion process when the process is started initially from a decreasing shock. This completes a study initiated in Ferrari and Kipnis [Ann. Inst. H. Poincare Probab. Statist. 13 (1995) 143-154].