investigation of one of the nation's premiere arson squads. Were they too good to be true? Here again is ABC's Byron Pitts. This is the damage done to the front living room. Reporter: Looking at video... See More
investigation of one of the nation's premiere arson squads. Were they too good to be true? Here again is ABC's Byron Pitts. This is the damage done to the front living room. Reporter: Looking at video taken by Phoenix fire investigators at Barbara Sloan's home which they believe she set on fire. Leading the investigation are captain Sam Richardson and Fred andies, they don't know it yet but they will soon find themselves under a cloud of suspicion and this is why. They brought in Sadie, the unit's arson going to find traces of accelerant. She does. But andies seems to expect more. Moments later, andies makes this stunning comment. Please fake it for me, okay. Fake it. Those word were unbelievable. I could not believe what I was hearing in his tone of voice, it was not just a joke. Show me. I was shocked. I don't understand why Fred andies did that. Sadie hit on the dining room. And hit in the kitchen area by the stove. Like the presence of ignitable liquid. Prosecutors dropped the case against Sloan saying Richardson was inexperienced that he had no evidence tying her to the fire. And all of his conclusions were speculative. Sloan filed a civil suit against the company. Deposition with the lawyers, captain Richardson admits he made up his mind before he had all of the fact. I knew when I left that day, that this was an arson fire. You want through this entire scientific method and concluded that Ms. Sloan's fire was arson that afternoon. Yes. You did it before you got any lab support back, right? Yes. Then there was captain andies turn. He was grilled about how often Sadie's results are confirmed by the lab. I don't know. Do you keep those statistics? No. Why not? I don't feel the need to. Didn't you think that is rel van Vant -- relevant to her reliability? No. Why not? I believe she is far superior to what the labs can do. You have no idea how right she is? She is right 100% of the time. They insist we follow the dog not what the test results found? How does that strike you? It is absurd to think that a 6-year-old lab retriever is smarter than than individual that has a college degree in chemistry. Reporter: It is true arson dogs often find trace amounts of accelerants that can't be confirmed by labs. That's because they're detecting trace elements too small to be meaningful, too small to help start a fire. So according to the national fire protection association, Sadie's alerts should never have Ben U been used. We wanted to hear more from andies but he decleanined our request for an interview citing a request. We showed up at his house. He didn't have much to say. I can't talk about it until they finish the investigation. We talked to the investigators. They say it won't be a conflict. Sir why is that you think? But andies did tell us something back in 2010. We used to think that we had to have concrete evidence. Reporter: Something in hindsight might explain a lot. Let's hear that again. We used to think that we had to have concrete evidence. And often we do. But now we have gotten smart enough now we can put a case together with circumstantial evidence and make it stick. We have done it time and time again. Where did andies pick up the attitude? Barbara Sloan says it all lead back to one man, jack Balentine, the maverick cop whose leadership led to the astonishing arrest rate. I believe he was pushing for the arson clearance rates to be the best in the nation. But it is okay, right, for bosses to be demanding and push their people to be the best, right? But it is not okay to enk encourage or push your people to be dishonest and not clearly investigate the facts. Reporter: Balentine decleanined a request for an interview. We tried to visit him at the station. Not expecting any one from the media. If you wait outside. Reporter: That we can do, yes, ma'am. I guess fire marshal Balentine does not want to see us, a man historically media friendly not so much today. Whennen we we caught up with him the following day. Good morning. Byron Pitt, ABC new, can we talk to you about the Sloan investigation? I take it the answer is no. There was one ray of sunshine for the Phoenix fire department. Barbara Sloan lost her civil suit. Though she is appealing the verdict. Their life goes on as though nothing happened. Nothing changed. And they have to know they did something wrong. They have to know. So today we stand at an impasse. The Phoenix arson squad stand by its accusation. But it is clear that mistakes made by investigators cripple the cases against Sloan and Capels, leaving both side with a sense of justice unserved. For more answers, we'll have to wait for the findings of that public safety investigation, expected out in the coming weeks. For "Nightline," I'm Byron Pitts, in Phoenix, Arizona. Our thanks to Byron Pitts for that report.
This transcript has been automatically generated and may not be 100% accurate.