there was joan, her husband bill bradford and their four children. this is joan's only daughter, shawn. >> people would describe her as the most caring, sweetest person they ever met. >> reporter: there were three boys, brett, the eldest. >> my mom loved her kids, we were first and foremost of what was important to her. >> reporter: the whole neighborhood knew that. >> neighbors loved my mom and would flat-out say, we didn't even know your dad. >> maybe that was in part because of bill bradford's job. bill worked as an aerospace engineer, very high security, top secret clearance at a company called trw. >> trw back in the '80s was an aero defense firm. >> top of the top. >> top of the top. >> so his reputation as work, did you know much about that? >> i knew he was good at what he did, but he was also very secretive about it. >> you just don't talk about it. >> yeah, you don't want talk about it. >> reporter: in fact, bill bradford didn't talk much about anything to anybody. even his own family. >> he was just very much, you know, here's my role. i wo