Osterman says Zimmerman's focus was on Martin's hands on his face, which kept him from breathing.
"It was critical. ... He was losing oxygen; he felt he was not able to breathe. That's why he was desperate to clear an airway," says Osterman.
Osterman says it's typical for someone to have tunnel vision in this type of situation and only focus on certain things.
[Updated at 12:09 p.m. ET]
The position of Martin's knees may have changed as Zimmerman squirmed, according to Osterman. Zimmerman said that it was Martin who straddled him and that Zimmerman was screaming for help.
[Updated at 12:07 p.m. ET]
Osterman says Zimmerman told him he went straight through to find an address, he didn't turn to go down the "T" in the sidewalk. When he was on his way back, Zimmerman said, the altercation began.
[Updated at 12:05 p.m. ET]
Osterman says it makes more sense for you to be able to keep an eye on a suspect while on the phone with the dispatcher.
Zimmerman told Osterman he lost sight of Martin at some point.
"That's one of the reasons he got out of the vehicle," says Osterman. He also says that as an officer gets on the scene, dispatch likes to ask for someone's exact location so they can meet up.
[Updated at 12:02 p.m. ET]
At some point, Martin walked around Zimmerman's car and the two made more eye contact, according to Osterman.
"Very aware of each other's presence," says Osterman. He says Zimmerman didn't seem angry.
[Updated at 12:01 p.m. ET]
Osterman says Zimmerman went to Target "every single Sunday, like clockwork." He says Zimmerman saw Martin going between homes, and the two made eye contact.
[Updated at 11:59 a.m. ET]
Zimmerman's wife went into "nurse mode" once they got into Osterman's car. She wanted to put ice on his injuries. Zimmerman explained what happened that night.
[Updated at 11:57 a.m. ET]
"Is detached different from the way he normally is?" asks O'Mara.
"Vastly," says Osterman.
Osterman says Zimmerman seemed to not be processing what was going on, describing him as having a blank stare.
[Updated at 11:56 a.m. ET]
Osterman says that Zimmerman was "stunned" and that he immediately tried to reassure his wife.
"He had a stunned look on his face. Wide-eyed, just kind of a little bit detached perhaps from maybe not realizing he had just gone through a traumatic event," says Osterman.