-- self defense or was it murder that's the question at hand during this second week of testimony in the explosive trial of George Zimmermann. The prosecution featured the suspect's own re enactment... See More
-- self defense or was it murder that's the question at hand during this second week of testimony in the explosive trial of George Zimmermann. The prosecution featured the suspect's own re enactment of the moment in question when he shot teenager -- on Martin. Tonight we welcome Nightline's new co anchor Dan Abrams in Sanford Florida with the very latest welcome down. Thanks to Jew behind me is the courthouse -- today for the first time the jurors heard from defendant George -- himself. As he described to police what happened the night he shot seventeen year old trade on Martin. And yet it was also a day -- the prosecution's witnesses and even Zimmerman is account. Seemed to many to helps it remains defense. As much as anyone. Do you know all right mr. -- -- totally -- a huge boulders come back. In court today. Prosecutors continued to make their case that George Zimmermann is guilty of murdering seventeen year old trade bond -- You were able to get into his mind as to why he followed. This person. Even though he hasn't taken the stand the jury heard from Zimmerman five separate times including an audio recording. Made by the Sanford police the night -- -- fatal encounter with mark. And a reenactment he did the next day. I try to sit up and that's when he grabbed me by the hand and tried to. Slam my head down. Zimmerman told police that he was just trying to defend himself. Reach for everything. His arm going down side. And I grabbed it and I just fire. The first police officer to respond -- was -- Singleton. And he says he's dead she testified Zimmerman didn't even know that Martin had -- She even to comforted him and I so wolf what you're telling me how it happened is true. Then I'll think that's what god that -- mean that you could save your own life. The collision courses Zimmerman and Martin took place here in this gated community eight miles from the courthouse on February 26 2012. Martin was walking back to a house where he and his father were staying Martin caught the attention of the self appointed neighborhood watch captain George Zimmermann. Who called police. They're -- crises. Smoker is under under armed they suggested he stay in his car. -- -- -- -- -- -- What happened next is in dispute. But there seems to be no question there was an altercation. Loud enough so that multiple neighbors called 911. The red -- -- in the back of my porch someone's yelling to sort -- the recent screening hollering help self help but it Kurdish shot right behind my help. Our. At issue who was attacking who. Zimmerman fired one gun shot and killed -- -- on Martin. Those 91 calls are crucial pieces of evidence because they can help determine who was the aggressor. But the FBI's audio expert testified today that it's impossible to tell who was screaming for help. -- -- Technology or sent the device. Put himself -- Weren't suitable to analyze the but particularly in all boys we. The -- thirty heard from neighbors who witnessed the confrontation. -- -- -- -- -- -- I didn't can't miss any time -- isolation. John good testified that he saw the man he now believes to be -- on top of Zimmerman beating it. Bolstering the defense's claim of self defense. Going back to -- -- were vertical I could tell that person on the bottom had a lighter skin color. We visited the gated community today what makes John -- testimony so important is not just what he said but where he wants. This is the spot where trade on Martin was shot -- -- That's where John good -- it seems day after day the prosecution's. Own witnesses. Bolstered George Zimmermann account. I haven't seen it that way I think this case. Is about putting the pieces of the puzzle together and that's what this prosecution has done. All along Zimmerman has been consistent all in his clean shot -- in self defense. Including -- reenactment that's -- Wall Street through here got Paris prosecutors played part of that in court today this news. Problems. Done. Zimmerman showed police the bushes from which he claims -- jumped down. The question raised in court today where are those -- George -- was referring to. This is the spot where he says trade on -- confronted him. There -- no bush is immediately here. But George -- would say that's where trade on Martin was -- the prosecution also wants to cast doubt on Zimmerman claim. He only got out of his car because he didn't recognize where he won. -- but I knew I went straight through. That's for Tuesday -- off and I. -- values of the house here in front of. He -- -- on up in my yard down here in the starts. Frank -- he's a former neighborhood watch volunteer who lived in the neighborhood for years up to the clubhouse. Where he makes his first 911 call. He supports Zimmerman says he can understand why Zimmerman was confused tonight Marten was killed -- -- -- that's how -- here six years I didn't know named mystery it was on. I don't even know it. Late today a potentially critical prosecution witness took the stance. Chris -- Reno the lead investigator in the case who interviewed Zimmerman. And recommended he be charged with manslaughter. And -- -- -- -- Kiran Benjamin Martin -- news -- imaginative but they were to -- his seventeen years old. Particularly future. Particularly -- -- care. But on cross examination his testimony -- -- don't seem to help. George -- America to -- take pathological -- off the table as a possibility just for the whole purpose of this next question. You think -- -- answers to this. The lead investigator says. His statement. Was pretty consistent and so either he's a pathological liar or he's telling the truth. But I think you need to take a step back and look at the direct examination it was also. Very very good very very strong and -- -- own words were challenged by the investigators and a solid something's off Baldwin. After hearing so much from George -- today will the defense even have to call into the stands tonight is attorney Mark O'Meara suggested to artists. That was unlikely. Ability to see something new before you so as of right now open -- honest man. Hate to say that I made that decision. I like -- -- -- is gone so far. Not calling his client in this self defense case would certainly suggest -- Mara is confident about the way the case is gone so far. But it -- you can never predict what happens next and lead investigator Serena is expected to be back on the stand tomorrow.
This transcript has been automatically generated and may not be 100% accurate.