Gilgo Beach serial killer Rex Heuermann’s lawyer revealed the two key reasons why he suddenly flipped and fessed up to viciously killing eight sex workers after years of maintaining his innocence. The hulking Massapequa Park architect’s defense attorney, Michael J. Brown, claimed his client finally decided to cop to the savage killings that have rocked Long Island for three decades to shield the victims’ families and his own from hearing the grisly details of his cold-blooded slayings at trial.