The trial of a US neighborhood watch volunteer accused of murdering a black teenager took a fresh twist on Thursday after jurors were told they could convict him of the lesser charge of manslaughter.
Hispanic defendant George Zimmerman faces possible life in prison if convicted in Florida of second degree murder in the shooting death of unarmed teen Trayvon Martin in February last year.
But during closing arguments in the racially charged trial Thursday, Judge Debra Nelson said the jury could convict Zimmerman, 29, of manslaughter, if they are unconvinced that the evidence proves he is guilty of the murder.
The move came as both sides in the case traded their differing assessments.
"A teenager is dead through no fault of his own, dead because a man made assumptions and acted on them, unfortunately, because his assumptions are wrong, Trayvon Benjamin Martin no longer walks on the earth," prosecutor Bernie de la Rionda told jurors in his closing arguments.
"He profiled him as a criminal. He assumed certain things -- that Trayvon Martin was up to no good. And that's what led to his death."
Zimmerman's attorneys protested the judge's decision to allow jurors to consider lesser charges, saying the jury should be given a clear choice -- either conviction for murder or acquittal.
"The state has charged him with second degree murder," said defense attorney Don West. "They should be required to prove it, if they can. If they can't prove it, then that is the failing of the prosecution.
"Had they wanted to charge him with manslaughter instead, because they think that's a better chance under their theory of prosecution -- whatever it may actually be, since we haven't heard it yet -- they could do that.
"We want this to go to the jury on second degree murder only."
Defense attorneys are to give their closing arguments Friday morning, before the six women of the jury start deliberations, either that afternoon or the following week.
Late Wednesday the defense rested its case without calling Zimmerman to the witness stand, after three weeks of evidence and testimony.
Zimmerman, a neighborhood watch volunteer, has been portrayed by prosecutors as a would-be cop who shot Martin during a confrontation in a gated residential community in the central Florida city of Sanford.
The trial has been nationally broadcast on US television, increasing anticipation and uneasiness over the verdict. Americans have been fixated by the courtroom drama, sending more than a million tweets each day about it.
During testimony Wednesday, attorneys from both sides straddled a foam dummy to demonstrate their respective versions of the fatal fight between Zimmerman and Martin. Each side claims the other instigated the hostilities.
Zimmerman said he phoned police when he saw Martin walking in a hooded sweatshirt in the gated community, which had seen a string of robberies.
He told police that he found Martin's behavior suspicious, and followed the youth even though he had been instructed by authorities not to do so.
Martin had been visiting a family friend in the neighborhood and was coming back from a convenience store just before his altercation with Zimmerman.
The defense said he was guilty of racially profiling Martin, but Zimmerman has denied any racial motive in the killing, saying he shot Martin only because he feared his life was in danger.
The trial has centered in part on Florida's controversial "Stand Your Ground" law, which permits a shooter to use deadly force if he believes his life to be at risk.