Did Miss Emily kill Homer Barron?

Faulkner never states outright that Miss Emily killed Homer Barron, but that's the beauty of modern writing; it follows Hemingway's "iceberg theory," wherein the writer focuses on that which is on the surface (the part of the iceberg that people see above the water) without discussing the underlying elements (the rest of the iceberg that floats under the water). 
But even though Faulkner does not state that Miss Emily killed Homer, there are plenty of clues. The most obvious clue is the arsenic that Miss Emily buys at the drugstore. When she comes into the store, Faulkner writes,

[S]he was over thirty then, still a slight woman, though thinner than usual, with cold, haughty black eyes in a face the flesh of which was strained across the temples and about the eyesockets as you imagine a lighthouse-keeper's face ought to look.

Her looks suggest that she is under extreme stress, perhaps brought on by the rumors about Homer leaving town without proposing marriage to her. And when the druggist asks for the reason she needs the poison, she only stares at him. The druggist is the one to write "[F]or rats" on the bottle.  Afterward, when Homer returns, once Miss Emily's relatives leave, the town never sees him again, even though "[A] neighbor saw the Negro man admit him at the kitchen door at dusk one evening." 
Another clue that Miss Emily killed Homer is the smell that lingers at her home. While the story is not told in chronological order, Faulkner writes that after Homer disappeared, Miss Emily was not seen outside of her house for six months, and that was the time when the men came over to sprinkle lime around her yard to rid the smell...probably of a decaying body!
And finally, the final clue, is Homer's dead body found in Miss Emily's room after her death. Again, while the text does not outright state that the body is Homer Barron ("The man himself lay in the bed"), the reader assumes that it is indeed Homer.