Even though Andrew James McGann is sitting in jail accused of the ghastly double murder of parents who were hiking at a state park in the Ozark Mountains, several key questions linger about why they were killed.

Authorities are now investigating Arkansas murder suspect for possible connections to unsolved homicides in Vermont and Wisconsin.

The man charged with fatally stabbing a couple with their kids at Devil's Den State Park in Arkansas pleaded not guilty Thursday to two counts of capital murder.