Clinton David Brin and his wife, Cristen Amanda Brink, were "fatally attacked" while out hiking with their two daughters at Devil's Den State Park, police said.

Prosecutors in Arkansas say Andrew James McGann left a hiking trail at a state park a bloody mess after stabbing a couple to death ... and folks saw him leaving the scene with blood on his face. In new legal docs,

Clinton David Brink, 43, and Cristen Amanda Brink, 41, were found dead Saturday at the park in Washington County, police said. They were hiking with their daughters, ages 7 and 9.