George Zimmerman murder trial: Prosecutors to unveil female friend of Trayvon Martin, who was on phone to teenager moments before he was killed

Girl received running account of events starting, she says, when Mr Martin noticed Zimmerman watching him in the gated central Florida community

A friend of Trayvon Martin, who claims she was talking to the teenager on the phone around the time he was shot dead by George Zimmerman, will appear in court today.

The girl, identified yesterday as "Rachel" but previously known only as "Witness B", is due to appear in court to describe what she says the unarmed 17-year-old told her in the moments leading up to his death.

"Rachel" received a running account about what was happening at the time starting, she says, when Mr Martin noticed Zimmerman watching him in the gated central Florida community that he was visiting.

In previous written testimony "Rachel" said that Mr Martin appeared scared and was trying to get away from Zimmerman. She was urging him to run. She last heard Mr Martin say, “why are you following me?” after which she said she heard what sounded like Mr Martin falling. Then the phone line went dead.

The Martin family lawyer, Ben Crump, has said her testimony helps destroy Zimmerman's claim that he acted in self-defence.

Yesterday, prosecutors told the court that Zimmerman shot and killed Mr Martin not in self-defence but “because he wanted to”. The jury heard details from the first call Zimmerman made to emergency services after spotting Mr Martin on the night of the killing. Phrases captured on tape, prosecutor John Guy said, included, “fucking punks, these assholes always get away”.

Also on view in the Sanford Criminal Courthouse was the distance between the two versions of what transpired on the night of 26 February last year, which has already divided public opinion across America.

Zimmerman, 29, who has Hispanic heritage, has pleaded innocent to the charges of second degree murder. His lawyers contend he fired his gun only after being assaulted.

“There are no monsters here,” Don West, a defence lawyer, said in his opening statement, denying the contention that his client had chased and then confronted Mr Martin who was black, in part because of his race.

“George Zimmerman is not guilty of murder. He shot Trayvon Martin in self-defence after being viciously attacked.” He added: “He shot Trayvon Martin because he had to, in self-defence”.

But the prosecution promised the panel of six jurors, who are all women, that it would prove that Zimmerman was never attacked by the teenager. From the start, Mr Guy said, the defendant had spun “a tangled web of lies” about the shooting to protect himself.

“George Zimmerman did not shoot Trayvon Martin because he had to. He shot him for the worst of all reasons – because he wanted to,” he said.

Just before the trial’s opening Judge Debra Nelson barred the prosecution from introducing testimony from voice experts who were to argue that screaming heard on another emergency call tape was that of Mr Martin. But Mr Guy said jurors would hear the call and be able to make up their own minds up.

“In the background, you will hear the gunshot that killed Trayvon Martin and you will hear screaming in the background. Listen carefully, please, to that call and listen carefully when the screaming stops. It’s right when the gunshot goes off.

“Trayvon Martin was silenced immediately when the bullet the defendant fired was shot through his heart,” Mr Guy said. The trial, which is expected to last several weeks, will be closely watched in part because of the national debate that was stirred by the killing and the decision by Sanford police initially to release Mr Zimmerman on the basis of Florida’s controversial self-defence laws known as “stand your ground”.

After outrage spread, especially in America’s black community, a special prosecutor was appointed to look into the case and Zimmerman finally turned himself in. The Sanford police chief was subsequently fired.

If found guilty, Zimmerman could be sentenced to life in prison.