Trayvon Martin murder trial opens with clash on shooter's motive SANFORD, Florida (Reuters) - Volunteer neighborhood watchman George Zimmerman, on trial for the murder of unarmed black teenager Trayvon Martin last year, killed him "because he wanted to" not in self-defense, a Florida prosecutor said at the start of Zimmerman's murder trial on Monday. In a fiery opening statement to the jury, Assistant State Attorney John Guy said the evidence would show that Zimmerman, 29, had spun "a tangled web of lies" about the shooting in a gated community in the central Florida town of Sanford. The killing triggered nationwide protests because Zimmerman was not immediately arrested and walked free for six weeks, after claiming he acted in accordance with Florida's self-defense laws when 17-year-old Martin attacked him. Zimmerman's lawyer Don West, in his opening statement in Seminole County Court, repeated many of the claims that have already been heard from Zimmerman, his family and lawyer. "There are no monsters here," West said, contesting Guy's description of his client as a would-be cop who was trained in martial arts and kick boxing and used "hate-filled" speech to describe an innocent young man. Zimmerman, who is part Hispanic, was the neighborhood watch captain in the Retreat at Twin Lakes community in Sanford at the time of the killing on February 26, 2012. He has pleaded not guilty to the charge of second-degree murder and could face life imprisonment if convicted. Martin was a student at a Miami-area high school and a guest of one of the homeowners in the Retreat at Twin Lakes. Neighbors who witnessed the scuffle and the fatal shot, albeit on a rainy night, are expected to testify during the trial. George Zimmerman did not shoot Trayvon Martin because he had too. He shot him for the worst of all reasons, because he wanted too," said Guy, the prosecutor, during a 33 minute-long opening statement. As he spoke, Zimmerman, who is out on bail and appeared in court wearing a charcoal gray suit, showed no emotion as he look straight ahead and away from the prosecutor. The prosecutor spoke of "irrefutable physical evidence" to prove that Martin was not the aggressor. Guy also said that Zimmerman's description to police of what happened was "physically impossible." There is a high bar for the prosecution, which has the burden of proof in a case that will center on Florida's aggressive self-defense laws. Zimmerman's lawyer focused on that during his opening statement to the jury of six and four alternates. "George Zimmerman is not guilty of murder," West said. He shot Trayvon Martin in self-defense after being viciously attacked. In instructions on "justifiable use of deadly force," that Circuit Judge Debra Nelson read to jurors, she noted that anyone in fear of grievous bodily harm or death is entitled to shoot and kill an assailant rather than back down.