Trick with talking TV is still simple. Everybody's attention was on TV. Owen could stand behind all of us and speak his lines to small microphone when no one was looking.
The purples belong to BP, Maya and Blackrune.
BP could lie about his opinion, but it isn't something we can determine.
Blackrune was telling the truth.
Maya told us she was called to Room I without corpses. This is pretty tricky, because we never were informed about the name of room with corpses. I think suspicion on Maya is misleading, at last to the extend of this purple, and I suspect that the information about names of rooms does have some use. The bodies were found in Room Eye, Maya could simply misinterpret Blackrune and lead us to wrong room.
Construction of the locked room.
Well, it says that none of victims locked it, the killer did not lock it from the outside, and since the door was locked the killer wasn't inside.
Last two confirm that the doors were not locked by the killer. I have two theories about it.
"None" is a playword, it means that not one of victims locked the room. After being stabbed all three of them locked the room using three separate keys. Dunno if I'm not stretching since I'm not native English speaker, but I know that "No one" can mean "not just one". At last their death wasn't confirmed to be instant.
Alternatively the room was locked by somebody else than one of victims or the killer. Let's say that Hershel discovered open room with corpses and then she had a "brilliant" idea to hide from the killer by constructing locked room. Only the killer was confirmed to not hide in the room, so anybody else could be hiding. Alternatively, Blackrune entered the room, did not look for the corpses, locked himself from inside, broke down the doors and discovered the corpses. He was so genre-savvy that he constructed locked room to find the bodies right away. Anyway If Hershel was hiding in the room, she left after us and used a shortcut to return to the lounge.
Now we have the most tricky part. No matter if Maya killed DWaM and Hersh, we have everybody being killed once Phoenix wakes up in Room E. The key to the trick is that you announce Phoenix to not be among killed, you tell him he is going to be shoot in 20 minutes, and you say that Phoenix also was murdered. It reminds me of phrase "you are already dead". You can be alive despite being "already murdered/killed/dead", if, for example, you are already poisoned and can't be saved. So In Room E Phoenix Wright has been "already murdered" and he was going to die soon and also Owen has been "already murdered" (by himself) and he was going to die after shooting Phoenix Wright to the head.
So how Phoenix and Blackrune were knocked out? Owen knocked us out using hidden remote device or At last one of victims was alive, despite being "already dead", and knocked us. They weren't killers accomplishes, they believed that one of us is the killer.
So who is the killer?
It isn't Phoenix Wright nor Blackrune.
BP, BB, and Tap were not the killer because they existed inside the locked room, unless a fake corpse was involved. It is possible, because Blackrune didn't bother with checking the bodies at all.
DWaM was with us for entire time before BP, BB and Tap were killed by being stabbed.
Hershel was inside the room with DWaM, but it could be a fake body.
So unless we have a fake corpse involved, it has to be Maya.
Okay, I'll take a shot.
U. N. Owen is Tap. Tap never spoke a single line during Owen's introduction because he was standing behind all of us speaking to some kind of microphone. This is why Tap was unnaturally calm and didn't say anything, he was avoiding attention to pull his little trick. Later Tap stabbed BP and BB, and put some sort of fake third corpse that nobody properly examined. He also stabbed himself, though it wasn't immediately fatal. From that point Tap was "already dead", either from the stab or from some sort of poison. Locked room was constructed by hiding Hershel or extremely genre-savvy Blackrune. It was possible for Hershel to arrive to lounge before us, even if he waited for us to leave the room with corpses. Maya was kidnapped/killed after she followed DWaM. DWaM or Hershel were "already dead" but still alive. Once we arrived it was them who knocked us out believing that one of us was the killer. Alternatively, DWaM and Hershel were dead in most literal sense and we were knocked out by some device. After that Tap killed Blackrune, he also put us in room E. Still, Phoenix was also "already murdered", but Tap was going to shoot his head in 20 minutes anyway. After doing so Tap was going to finally pass away. It is possible that this really was only "the first murder" before any crime was discovered, Tap could poison everybody before stabbing BP and BB.