dr. wheeler never found a single case of severe black lung in any coal miner not one. dr. y the cases? >> absolutely. that's my opinion. a perfect right to my opinion. >> reporter: you have become dr. no. you never find. >> i do find black lung. >> reporter: not according to what we have seen. not severe black lung that allows miners to collect benefits. hopkins says their doctors have confirmed thousand of cases compatible with black lung over the last 40 years but would not say how many were severe black lung. in court testimony, last year, dr. wheeler said that last time he recalled diagnosing a case of severe black lung was in the 1970s or early 80s. your reports and your testimony has led hundred of thousands of miners to be denied benefits that they think they deserve. >> i have no idea what happens when the x rays leave my department. >> does it matter to you? >> it would matter to me that i am wrong. no one has proven i am wrong. >> reporter: our investigation found,000 thee h he has been wr on cases of miners where awe top sees found black lung after dr. wheel hear

dr. wheeler's medical findings. >> there is movement in congress on this? >> senator rockefeller introduced legislation to pursue a way to end what he calls the injustice, the imbalance between the powerful coal companies and the miners but he says it's a tough fight. they suffer in silence, and there hasn't been much attention paid to it until tonight. >> you're going to have much more tonight on "nightline." >> that's right. >> thanks very much. >>> now a story about a modern day good samaritan, a bus driver doing his rounds on an ordinary day when he sees something others chose to miss and does exactly the right thing. it was all caught on tape and abc's linsey davis brings us his story. >> reporter: call it a real life instance of what would you do? watch as surveillance video captures the moment darnell barton spots a woman standing on a narrow ledge on the other side of the guardrail, apparently contemplating jumping onto a local express way below. this man walks right by, this biker keeps on pedaling but barton pulled over and stops the bus. >> miss,

dr. wheeler's opinions, the coal companies have paid hopkins millions of dollars. >> you have essentially become dr. no. you never find. >> i do find. >> reporter: according to records from the last 13 years, examined by abc news and the center for public integrity, of 1,573 cases dr. wheeler never found a single case that would automatically qualify a miner for benefits, not one. >> you stand by all those cases? >> absolutely. that's my opinion and i have a perfect right to my opinion. >> reporter: based on the opinions of dr. wheeler and a small circle of other expensive doctors, coal miners across appalachia, men like mack lester are fighting a losing battle to get black lung benefits. at best fewer than one in ten is successful. >> i have no idea what happens once the x-rays leave my department. >> does it matter to you? >> it would matter to me if i were wrong and no one has proven to me that i'm wrong. >> reporter: we found he's been wrong a lot in over 100 cases including that of gary fox. it was only after fox died that an autopsy proved fox had black lung. after wheeler's opinion