They could use both, like in the Aurora/Holmes case. it does appear that poor James Holmes has been screwed up with either drugs or mind control or both. But he may not have done any shooting either - it was probably a professional hit squad of 2-3 men.

While I can see the usefulness of mind control on the patsy (think back to Sirhan Sirhan), the actual killing would be more effectively done by an actual professional killer. There are a lot more of them in the world than we realize, and they would be willing to kill all kinds of victims, including children.