The desperate hunt for the murderer who killed a married couple in front of their young daughters at Devil’s Den State Park in Arkansas was stepped up Monday — as cops also scrambled to justify taking six hours to alert the public that a double killer was on the run. Calls first came in at 2:30 p.m. that there was a potential assault in the eerily named state park — with first responders then hearing screams, according to 5News.By the time they caught up to the family, it was too late, and parents Clinton David Brink, 43, and Cristen Amanda...