"When she kind of comes out of those semi-dream, twilight states, she is very vocal with tidbits that come sentence by sentence," Heilman said. "She's reliving things in her mind. She calls out for Christina, she talks about the impact of the bullets and that dramatic sense of bleeding out on the ground."
Heilman said Christina's parents have reached out to him, sending him e-mails and talking by phone.
"That is one of the more mind boggling aspects of this, the level of grace that the Greens have shown for what we're going through is above and beyond. ... We shouldn't lose our babies this way," Ben Heilman said.
Pam Simon, one of two staffers for Giffords who was hospitalized with injuries, is almost fully recovered, her son said.
"We're very happy that she's recovering so well, but I do need to acknowledge we feel very fortunate," Fritz Simon said. "A lot of people were hurt on Saturday, and a lot of lives were destroyed."
Simon said that his mom did see the shooter, and he thanked a good Samaritan who helped save his mother.
"I know that after she was hit. She lay face-down and tried to keep still, but there was a Samaritan that came along and stayed with her. He said he's going to stay with her, and he took her cell phone and called my father," Simon said.
The memorial, "Together We Thrive, Tucson and America," will take place on the University of Arizona's campus at 6 p.m. MT.
ABC News' Devin Dwyer, Tonya Kerr and Desiree Adib contributed to this report, as well as The Associated Press.