Is This a Sign of a Serial Killer?

Five out of the six were cats with an additional one tiny dog. From what we could tell they had all been strangled or had their throats cut. The decision was made to get Isaiah counseling and that's it. No one has had contact with Isaiah in over seven years. His name does come up in searches but he makes sure to move around a lot. So far he shows up in Denver, Los Angeles, Chicago and most recently Long Island.