[Updated at 11:53 a.m. ET]
O'Mara asks if their friendship would affect the way Osterman testifies.
"You're going to speak the truth, good or bad, for Mr. Zimmerman?" asked O'Mara.
"Correct," said Osterman.
He says that Zimmerman's wife was "indescribably hysterical" and that he had to put his arm around her to keep her from blacking out.
[Updated at 11:51 a.m. ET]
Osterman has been in law enforcement since 1992 and helped Zimmerman buy his gun.
"He asked whether he should or shouldn't, to start with, and I recommended that he should. Anybody who's a nonconvicted felon should carry a firearm. ... The police aren't always there," says Osterman.
[Updated at 11:49 a.m. ET]
Osterman says the place where Martin grabbed the gun seemed to be where it was being held by the holster, which is why he didn't say Martin grabbed the holster. Prosecutor de la Rionda has finished his questions.
[Updated at 11:47 a.m. ET]
Zimmerman told Osterman that he had been instructed, in general, to "get where you can observe and try not to make contact."
[Updated at 11:46 a.m. ET]
"After putting his gun back in the holster, he jumped on top of Trayvon Martin and pinned him down," says de la Rionda.
"That's correct," says Osterman.
[Updated at 11:44 a.m. ET]
Zimmerman told Osterman he believed Martin felt the gun with his leg and then grabbed for it.
"He says, 'You're going die,' and he used the MF term again. I'm sorry I don't like to curse in front of ladies," says Osterman.
Zimmerman told Osterman that he grabbed the gun out of Martin's grip and shot him. Martin told him, "You got it" or something like that. Zimmerman says he then scooted out from Martin. He says he didn't believe he hit him.
[Updated at 11:42 a.m. ET]
"One hand was trying to cover his nose and one hand was trying to cover his mouth to keep him from screaming," says Osterman.
Zimmerman told Osterman that because his jacket had ridden up, Martin may have seen he had a gun. Zimmerman was trying to remove Martin's hands so he could breathe and scream.
[Updated at 11:39 a.m. ET]
"Once he started screaming, George said Trayvon grabbed his head and started smashing it into the concrete," says Osterman.
As Zimmerman squirmed to get his head off the concrete, his jacket came up, according to Osterman. Zimmerman said he directed his screams for help at the people who came out.