We now know what the defense lawyer knew all along. We know who did it. Yet Feldman willfully, knowingly, and viciously slandered and falsely accused many innocent people, suggesting they kidnapped and killed little Danielle. He slandered Westerfield's own son and accused him of downloading kiddie porn.
You might find such wholesale serial slander ethical. I do not.
"Reason to suspect" is not the same as "know." There is NO evidence, even anecdotal, to establish that Westerfield ever told his defense team that he committed the murder of which he has now been convicted. No detective is even stepping up to the plate to take responsibility for the report that Westerfield even volunteered the location of the body (which he could logically have known without having personally committed the murder).