Told you so. IMO hiring Greenspan and the investigator is more about PR than it is about finding the answer. The family now has carte blanche to throw out whatever theories they choose. The public will always buy it because, lets face it, the public loves a good conspiracy theory.
The "no forced entry" is just part of what likely led LE to think this was murder/suicide. Cops have the benefit of knowing whose fingerprints were where, if Barry had defence wounds, if there was any sign of a struggle, cell phone records, timelines, etc., they don't just come to determinations based on the fact that there didn't appear to be forced entry.
What doesn't make sense to me is that if this was a murder, why the murderer would possibly take a key (and I assume all keys are accounted for) and lock the door after he left? Just doesn't make sense.