CNN News:美國(guó)槍殺黑人少年案出現(xiàn)強(qiáng)有力證據(jù)

Hey, I'm Anderson Cooper.

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Powerful testimony in the George Zimmerman trial.

A new video of the terrifying moments after theplane crash in San Francisco.

Let's get started.

We begin, though, with a late and possible key development in the George Zimmerman trial.

The judge this afternoon allowing attorneys for George Zimmerman to introduce evidencesuggesting that Trayvon Martin had smoked pot before he died.

Prosecutors fought hard against it, calling it a backdoor way of tarnishing Trayvon Martin's character in the eyes of the jury.

Zimmerman's drug use has also come up firing EMS report showing he was on anxiety and sleep medications the night of the shooting.

There's yet to be a ruling though on the admissibility of that evidence.

And there was much more today than just the pot rulings, a powerful step as Martin Savidge reports.

He joins us now live. Martin?

Yeah, Anderson.

It was a day of just significant surprises again.

And one of the questions that had been asked, really, to the defense team was will they are gonna call Tracy Martin, Trayvon's father.

Because if you remember,

it had been reported that Tracy Martin, when he heard that 911 call with those terrible screams, he had told the authorities that he did not hear his son.

And in fact, they brought two testimonials that were brought on by the investigators who said: "Yeah, that's in fact what he told us that we played it and he said he didn't hear his son."

Bet then, Tracy Martin comes to the stand called by the defense.

Well, let's just listen to how the day went.

" … and nothing but the truth, so help you God?"

It was another remarkable moment, the father of Trayvon Martin taking the stand, questioned by the attorney defending the killer of his son.

Earlier two police investigators testified that just days after the shooting,

they played Tracy Martin the 911 call containing screams and a gunshot from that night.

Both said Tracy Martin unequivocally told them it was not Trayvon he heard screaming.

But on the stand Martin testified he never said and said he told police he wasn't certain whose voice he heard.

What was going through your mind when you were listening to that?

Basically, what I was listening to, I was listening to my son's last cry for help.

I was listening to his life being taken.

And I was coming, trying to come to grips that Trayvon was here no more.

The defense had spent much of the morning hammering home a version of who was screaming for help.

One after another, five friends of George Zimmerman took the stand and, asked the same question, gave the same answer.

Definitely, it's Georgie.

I thought it was George.

When I heard the tape, my immediate reaction was that's George screaming for help.

Whose voice is it?

George Zimmerman's voice.

The most powerful affirmation came from John Donnelly, a friend of Zimmerman's,

who unlike any previous witness said he had heard voices under similar stress as a medic in the Vietnam War.

When someone is in dire straits , whether it be combat or anything else, your voice obviously changes.

I have heard a 250-pound man sound like a little girl screaming, and, but before you get there, you know who he is.

Instead of the scream, the prosecution focused on Zimmerman's language in his call to police,

suggesting his use of profanity implied hatred,

a key point when trying to prove second-degree murder.

It seemed to me when Mr.de la Riondo was trying to highlight it, make it sound heightened, and I don't feel that it was that way all.

I think it was more of a statement.

Also called to testify was the owner of the gym where Zimmerman trained in grappling and boxing for less than a year as part of a weight loss routine.

Asking him how he would rate his fighting skills?

What number would you assign to his abilities?

Point-five.

Less than a one?Yes.

Adam Pollock, a martial arts expert, demonstrated the so-called ground and pound techniqueof fighting that a witness last week said he saw Trayvon Martin use while stopped Zimmerman on the night of the shooting.

Pollock, who is also a trainer, said he's seen his share of fight aftermaths and said that just days after the confrontation with Trayvon Martin, Zimmerman appeared black-eyed and emotionally traumatized.

Martin Savidge, CNN, Sanford, Florida.