covering it up. and reports confirm the corruption ran all the way to the top. >> former l.a. county undersheriff convicted of corruption in the same case that ended the career of former sheriff. >> in the wake of the scandal, it was clear the system needed a major overhaul. assistant sheriff terry mcdonald was the one appointed to the job. >> at the height of the controversy, what would you say went wrong? >> it's a high-stress environment. sometimes it's who you hired, but oftentimes it's really a lack of that front line supervision where you see an employee starting to lose their patience, you're not disrupting that. i don't think we trained people as well as we could have or should have. >> so what changes have been implemented in response to the allegations of inmate abuse? >> we've increased supervisors. we have more sergeants helping the staff with these complicated issues. fundamentally, we made it crystal clear that we're not going to tolerate prisoner abuse.