Some sites have alleged eyewitnesses claiming that Holmes had accomplices either letting him in to the locked theatre exit door, or throwing smoke cannister(s). In the Norwegian Breivik affair, there were indications that there were other shooters on that island. Possibly even police or those dressed in police uniforms (again other than Breivik.)
It would not even surprise me if Holmes did not fire any fatal bullets, but was drugged or hypnotized and others did as was the case with Sirhan Sirhan. In the Robert Kennedy Assassination, there are indications that Sirhan fired blanks. In any case, RFK was shot from behind, while Sirhan was in front of him. This leads to the issue of whether witnesses in the theatre will be prevented from speaking the truth–including killing them if they try…
While the lone nut nonsense is bandied about, per usual, the RFK Assassination indicates that about a dozen agents were there in various roles, including the actual shooters. This may be the case in the Aurora mass murder as well.
With Holmes a patsy controlled in some way after they messed up his mind.