Secret Service Officials are allowed to do that?

John Roth hold a very high position at the Department of Homeland Security, shielded by law from outside pressure so that he can figure out the government's business. Recently, he was investigating the Secret Service and allowed officials from the service to work with him and his agents to figure out how bad information concerning a member of congress was kept from the agency. (Jason Chaffetz of Utah who is the chairman of a House committee overseeing the agency was once rejected for a job as an agent. Apparently, the involvement of the officials in the investigation threatens the integrity of it. This could be a problem if top officials at the agency want to embarrass Chaffetz and could hinder future members for coming forward with allegations of misconduct. It doesn't make sense to me why they would allow people that work for a certain agency investigate their own, they could cover up so many things and would definitely offer a biased opinion. It just doesn't add up. What is the need for this? I see it causing more problems than helping because it taints the reputation that the DHS has.