Perhaps Barry wasn’t lying about taking a polygraph because maybe his attorney had him take one. Maybe it didn’t turn out well and he and the lawyer are not required to disclose the fact that one took place or what the results were?That's what the brother claimed, sure. I'd have found him more credible if he would've stated the date(s), time(s) and name(s) of the CBI agent(s) that supposedly told him the information.
As for the 30 hours of interviews w/o a polygraph request: if Barry Morphew is represented by an attorney who arranged the interviews, you can bet that one of the ground rules would be: No mention of polygraphs, either by police or Barry. If police didn't want to accept those ground rules, they could've rejected the interview offers.
Seems like you were a good candidate to ask! TIA