The Torah in ויקרא )טז:ו( states ויקרב אהרן את פר החטאת אשר לו וכפרו בעד ביתו. The Chachamim in Mishna Yoma understand this כפרה to be a source of verbal confession of sins. How did the Kohen go about doing this? He would simply say - "Hashem, I have sinned against you, I and my household...". We find a second reference to atonement in Pasuk יא. Rashi comments that the second confession is for himself and his fellow Kohanim, all which are included in the phrase "household."
The following question is obvious: Why is there a need for a second confession? Couldn't the Pasuk have worded itself to include the other Kohanim as well? It could have said "I have sinned, and my household, and the sons of Aharon too."
ריש לקיש answers the above question based on צפניה. It says תתקשט וקשוט, which is understood to mean - "first correct yourself and then correct others". So to fit in to the Kohanim's atonement, it is better that one which is already cleared to come and make atonement for the guilty, rather than the guilty atone for the guilty.
We can see from this that the focus of Yom Kippur is self purification and not accusing others of sin. Before we criticize others we must improve ourselves as much as possible.