mr. chamberlain's medical records. n chamberlain is a man who couldn't walk up a flight of stairs without having respiratory issues, that's why he wore that pendant around his neck in case he needed medical attention. it went off on november 19, an ambulance was dispatched. a security camera captured the police arriving there and kenneth chamberlain is called by the medical alert company who talks to him over a speakerphone. you can hear him telling them he's okay, he wants the police to go away. he said, they're going to kill me or beat me up. another point, you hear the medical alert dispatcher calling the police saying he doesn't need them anymore and he tells mr. chamberlain they won't go away unless he talks to them. i want to show you video that's mounted on the taser gun. take a look. >> okay. what are you doing. >> open up. >> leave, leave! >> open the door just so i can check you out. >> i'm okay. i'm fine. >> yeah, but -- >> i am fine. >> i'm fine. >> so how long does this go on for? >> it goes on for about 20

mr. chamberlain's medical alert pendant. this happened last november. mr. chamberlain signalled the alert system that called police. when officers arrived, he made it clear he didn't want them coming in. >> i'm okay. >> i need to see that you're okay and we'll go. >> you leave. >> can't leave. >> i'm okay. >> all right. i need to see you. >> i'm okay. >> he said that again over and over. several more minutes of tape that he wants police to go away. his son said he feared for his life. he was holding a knife when police opened a door. they fired nonlethal bean bags at him. we'll talk to mr. chamberlain's son shortly. first more on the tapes and the timeline and the grand jury's decision. soledad? >> the white plains district attorney said this entire incident was tragic from all sides. and i think that's fair to say. i have seen mr. chamberlain's medical records. he couldn't even walk up a flight of stairs without having respiratory issues. that's why he wore that pendant around his neck. it went off and an ambulance was dispatched. a security camera captured

mr. chamberlain the "n" word. meanwhile, police inside the building are using bolt cutters to get into chamberlain's apartment. they believe he's used a chair to block the door. at 6:41, more than han hour after they arrive police finally get chamberlain's door open. they say he's waving a butcher's knife above his head and they tase him. seconds later, they tase him again. >> go [ bleep ] >> at this point, police turn off the taser camera. this is the last image we have of kenneth chamberlain alive. police say he continued to come at them with a knife, so they shot him with several bean bags from a shotgun. police say when that didn't stop him, one officer fired his pistol twice. one bullet hit chamberlain in the lung, killing him. at 7:09 a.m., just about two hours after a medical alert dispatcher calls to see if a former marine is okay, kenneth chamberlain is pronounced dead. now joining me is criminal defense attorney mark geragos, also marcia clark former los angeles deputy district attorney and the author of