NEW : Would-be parents tell HLN they volunteered for polygraph tests . `` So her idea was to just keep running forever . Logan McQueary , December 26 , has n't been seen since 8 months old . Child 's mother was arrested in Arizona and is in police custody but wo n't say where he is . Police believe they Miami couple know more than they 're saying .
NEW : Would-be parents tell HLN they volunteered for polygraph tests . Logan McQueary , December 26 , has n't been seen since 8 months old . Child 's mother was arrested in Arizona and is in police custody but wo n't say where he is . Police believe they Miami couple know more than they 're saying .