You don't have to look. My guess is, most aren't. I've looked ever since they arrested him. As of yet, I've found no case where someone was convicted of AK without either a body or witness.
As to murder, again, there is a whole website that is up to 96 pages worth of murder convictions without bodies.
So, again, why wait? The murder charge, in my opinion, would do two things: (1) put real pressure on EA to talk if others were involved, and/or (2) have him and his attorney scrambling to a plea deal, if he were the only one involved because there is death penalty in Texas.
As of now, they are charging him with a crime which, has yet to have someone convicted without a witness or boy. And, he isn't even indicted yet. So, I ask again, where is the pressure on him?
If another party was involved, and it was a drug-related thing, he's living by "snitches get stitches" to protect himself and his family. His attorney has probably also already advised him of the rare, and perhaps novel, concept of an AK conviction without witnesses or body.
What was he doing anyway? Managing a Sprint store? Living with his parents? Okay, so what? He and his attorney probably figure he can wait out against an AK, again, because of the novelness and rareness of the charge.
Murder, I think would move the needle, and move it quickly.
In my opinion, the PD/prosecution might still believe there is a third party involved, and that's why they haven't made the murder charge. Which, again, in my opinion, is a mistake. The closer you get to watching your life be taken away, the more likely you are to talk, I think.
AK without witness or body being apparently unprecedented, I don't think the pressure on him is high enough. I say turn the pressure all the way up. There is plenty of case history to support the murder without a body charge, and none yet discovered of an AK without witness or body.
Go for the throat, I say, and end this thing that the families involved are having to live through.