"I know, Justin," his mother replied. "But I guess maybe the help wasn't working like we thought it was."

The kids were too young to understand acronyms like PTSD or to hear a lecture about how Knapp thought the system had failed Dwyer. So she told them that, just as they sometimes have nightmares, "sometimes people get those nightmares in their head and they just can't get them out, no matter what."

Despite the efforts she made to get help for Dwyer, Knapp is trying to cope with a deep-seated guilt. She knows that Dwyer shielded her from the images that had haunted him.

"I think about all the torture that he went through when he came back, and I think that all of that stuff could have happened to me," she said, stifling a sob. "I just owe him so much for that."

Since Dwyer's death, Justin, now 9, has taken to carrying a newspaper clipping of the Zinn photo around with him. Occasionally, Knapp will catch him huddled with a playmate, showing the photo and telling him about the soldier who used to come to his school and assemble his toys.

Justin wants them to know all about Spc. Joseph Dwyer. His hero.