The people that lied to Congress were from the office of Inspector General - Department of Homeland Security, the lead investigator of this incident since day one! They most certainly were involved!
The people who testified work in the same department of the government as the people who did the investigation. They are not the same people as those who did the investigation. Sanchez did not talk to the congresspeople, for example.
My point which is both clear and germane is that lying to congress about what evidence you have in investigative reports has no bearing on what evidence was presented at trial that convicted the agents.