Sanhedrin 43 - Distance Between The Court and the Place of Execution
There are four points of commonality between execution and the law of bulls: removal, outside the camp, preparation (both prepare for something), and atonement (both atone). There are also four points of commonality with the forbidden sacrifices: they apply to a person, a sinner, a life being taken, and sacrificial disqualification does not apply.
However, we should rather compare those laws that prepare for something, thus execution is compared to the law of bulls, and the place of execution is removed three camps from the courthouse.
Art: Arab Encampment in the Atlas Mountains by Eugene Fromentin
