(CNN) -- HLN, CNN's sister network, is covering the George Zimmerman trial, gavel to gavel. Zimmerman is charged with second-degree murder in the death of 17-year-old Trayvon Martin on February 26, 2012. Here is testimony from Monday:
[Updated 5:23 p.m.]
Under cross examination Serino testified that Zimmerman did not seem "cagey" or to be sidestepping questions.
Serino testified that he thought Zimmerman's affect was flat, consistent with having experienced trauma. Serino expresses concern for Zimmerman in audiotaped interview.
Serino testified that no major discrepancies come to mind regarding accounts given by Zimmerman at different times or with other witness accounts.
[Updated 3:03 p.m.]
Under direct examination, Sanford Police Investigator Chris Serino testified that Zimmerman said Trayvon Martin came out and punched him and told him he was going to kill him.
[Updated 2:30 p.m.]
Under cross examination, Sanford Police Investigator Doris Singleton said Zimmerman never refused to speak to police, was fully cooperative
Singleton testified she had no information at the time to dispute or corroborate Zimmerman's account
Singleton said she was not concerned that Zimmerman referred to Martin as a "suspect."
Singleton testified that Zimmerman never expressed anger, hatred, spite or ill-will or bad attitude.
[Updated at 12:29 p.m.]
Judge Debra Nelson has recessed court for lunch. The running update will pick back up when testimony resumes at 1:30 p.m. ET.
[Updated at 12:26 p.m.]
Zimmerman's signed his sworn written statement.
[Updated at 12:24 p.m.]
Occasionally, Singleton has difficulty reading Zimmerman's written statement, which seems to match up with what Zimmerman told Singleton during the recorded interview.
[Updated at 12:20 p.m.]
De La Rionda is showing the jury Zimmerman's written statement. Singleton is reading the statement as it is displayed on an overhead projector.
[Updated at 12:16 p.m.]
Zimmerman's written statement is four pages long.
[Updated at 12:14 p.m.]
Singleton also had Zimmerman make a written statement the night of the shooting.
[Updated at 12:11 p.m.]
Zimmerman told Singleton he got out of the car to check an address on a town home so he could give dispatch a better address for police officers responding to the scene.
[Updated at 12:08 p.m.]
De La Rionda has zoomed in on the map to show where Zimmerman was driving when he spotted Martin. The scribbles on the map were made by Zimmerman the night of the shooting.
[Updated at 12:03 p.m.]
Zimmerman takes a few minutes to show Singleton on the map where everything took place the night of the shooting.
[Updated at 11:58 a.m.]
Prosecutor De La Rionda stops the tape and asks Singleton why she showed Zimmerman a Google map of the neighborhood during the interview the night of the shooting. She said she didn't completely understand the locations he was talking about. Zimmerman drew points on the map where he first saw Martin, and where the altercation occurred.
[Updated at 11:57 a.m.]
"He puts his hand on my nose and my mouth, and he says 'you are going to die tonight,' " Zimmerman said on the recording.
"As he banged my head again, I just pulled out my firearm and shot him.
"He is mounted on top of me, and I just shot him, and he falls off. And he's like "All right, you got it, you got it."
[Updated at 11:55 a.m.]
Zimmerman said, "He was wailing on my head, and I started yelling 'help.' When I started yelling for help, he grabbed my head, he started hitting my head into ..."
[Updated at 11:53 a.m.]
After Martin allegedly punched Zimmerman in the face, he fell down on the ground.
"I tried to defend myself. He just started punching me in the face, and I started screaming for help. I couldn't see. I couldn't breathe," said Zimmerman.
[Updated at 11:51 a.m.]
Zimmerman said he was walking back to his car when Martin surprised him.
"He jumped out from the bushes, and he said, 'What the [expletive] is your problem, homie?' And I got my cell phone out to call 911 this time, and I said, 'I don't have a problem.' And he goes, 'No, now you have a problem,' and he punched me in the nose," said Zimmerman.
[Updated at 11:48 a.m.]
Martin cut through the middle of Martin's neighborhood, according to Zimmerman.
"The dispatcher told me 'Where are you?' And I said, 'I am trying to find out where he went.' And he said, 'We don't need you to do that.' And I said, 'OK,' " said Zimmerman.
[Updated at 11:45 a.m.]
Zimmerman tells Singleton said Martin circled his car, and then he went back into the "darkness," while he was on the phone with police.
[Updated at 11:43 a.m.]
Martin's father, Tracy Martin, is periodically closing his eyes as the police recording is played for the jurors.
[Updated at 11:41 a.m.]
During the interview, Singleton retrieves Zimmerman's cell phone from outside the interview room. Zimmerman looks up the phone number of the president of his neighborhood's homeowners association so he can help law enforcement retrieve tapes recorded by the neighborhood surveillance system.
[Updated at 11:39 a.m.]
Zimmerman is not showing any emotion as the recording of his interview with police from the night of the shooting is played for the jury.
[Updated at 11:36 a.m.]
Zimmerman told Singleton he did not recognize Martin as a resident of his neighborhood.
"He (Martin) was walking causally, and it looked like he was trying to get out of the rain," said Zimmerman.
[Updated at 11:33 a.m.]
"There's been a few times where I have seen a suspicious person in the neighborhood, and would call the police nonemergency line, and these guys always get away," Zimmerman told Singleton.
[Updated at 11:30 a.m.]
Singleton asked Zimmerman to tell him what happened and why it ended in a boy getting shot.
"The neighborhood has had a lot of crimes," said Zimmerman on the recording of the police interview. "So I decided to start a neighborhood watch program in the neighborhood."
[Updated at 11:28 a.m.]
Singleton says she told Zimmerman that the interview was being recorded.
[Updated at 11:27 a.m.]
Prosecutors are now playing Singleton's interview with Zimmerman the night of the shooting. On the recording, Singleton can be heard reading Zimmerman his Miranda rights.
[Updated at 11:25 a.m.]
Singleton saw that Zimmerman had blood on his nose, and the wound on his head was "actively bleeding."
[Updated at 11:23 a.m.]
Singleton says she did not threaten Zimmerman that night to get him to make a statement. She also observed no indication that he was under the influence of narcotics that night. Zimmerman said at the beginning of the interview that he did not think he needed medical treatment, but later in the interview, he said he was unsure if he needed medical treatment, Singleton says.
[Updated at 11:21 a.m.]
Zimmerman was informed of his Miranda rights before being interviewed.
[Updated at 11:20 a.m.]
Zimmerman was brought into an interview room that was about 5 feet by 8 feet. She conducted an interview with Zimmerman, and it was recorded with audio equipment.
[Updated at 11:18 a.m.]
The night of the shooting, Singleton was told to report to the police department. She did not respond to the crime scene.
[Updated at 11:17 a.m.]
Singleton was a narcotics investigator in February 2012, and she was on duty that night.
[Updated at 11:15 a.m.]
Prosecutors have called Sanford Police Investigator Doris Singleton, the 24th witness for the prosecution.
[Updated at 11:13 a.m.]
The jury is being seated.
[Updated at 11:11 a.m.]
Prosecutor Bernie De La Rionda has asked the judge to consider some jury instructions he has hashed out with the defense.
[Updated at 11:09 a.m.]
Zimmerman is back in the courtroom. Testimony should resume shortly.
[Updated at 10:54 a.m.]
The attorneys have finished their questions for Nakasone, and he has been excused. Court is now in recess for 15 minutes.
[Updated at 10:53 a.m.]
Nakasone says computers cannot determine the emotion, so investigators must rely on the trained ear.
[Updated at 10:51 a.m.]
Prosecutor Mantei has finished his questions for Nakasone. Now West is asking him questions on recross-examination.
[Updated at 10:49 a.m.]
Nakasone is explaining how a group of people can create bias in the group when listening to a voice sample in attempting to identify the voice.
[Updated at 10:46 a.m.]
Nakasone said he can only give law enforcement guidance on conducting voice analysis. He said he cannot control what methods they use.
[Updated at 10:44 a.m.]
West has finished his questions for Nakasone, and now prosecutor Mantei is now asking him questions on redirect examination.
[Updated at 10:43 a.m.]
West has asked for a moment to review his materials.
[Updated at 10:41 a.m.]
West asked, "I think with all of that, what you are saying is science really doesn't help us in this case figure out who is screaming?
"Unfortunately, that is correct," said Nakasone.
[Updated at 10:38 a.m.]
Nakasone said it is not possible to reliably determine people's ages when analyzing their screams.
[Updated at 10:34 a.m.]
West is asking Nakasone about how he determined whether the person on the 911 call was screaming under extreme stress or was in a life-threatening situation.
"Yes, it was uttered under an extreme emotional state," said Nakasone. Because of the extreme emotional state of the person screaming, Nakasone recommended to the FBI field agent investigating the Zimmerman case to not conduct voice analysis of the recording.
[Updated at 10:28 a.m.]
Nakasone said a voice sample needs to be a certain length to establish the signature of someone's voice. He said a voice sample of normal speech that is 15 seconds long can be analyzed, but the analysis would be better with a sample that lasts 30 seconds or longer.
[Updated at 10:25 a.m.]
Nakasone said that after isolating the screams on the 911 call, he only had 2½ seconds of clean of audio of the screams.
[Updated at 10:23 a.m.]
West is moving a copy of Nakasone's resume into evidence. West said this version is more complete.
[Updated at 10:22 a.m.]
West is asking Nakasone about examiner bias when a group of people are asked to recognize a voice when they listen to the sample while they are in a room together. Nakasone said there is a risk of bias in the results, because people can influence others' perceptions.
[Updated at 10:13 a.m.]
Nakasone is explaining how examiners conducting voice analysis can have a bias, and therefore it can affect their analysis in a negative way. The attorneys are now at a sidebar with the judge.
[Updated at 10:09 a.m.]
West is asking Nakasone about his working with FBI and how he works with training field agents.
[Updated at 10:06 a.m.]
Nakasone said voice analysis can be used for investigative purposes even if it is not admissible at trial.
[Updated at 10:03 a.m.]
The science of voice recognition cannot reliably analyze screams at this stage, according to Nakasone.
[Updated at 10:01 a.m.]
Nakasone is explaining how MIST conducts analysis of voice samples.
[Updated at 9:58 a.m.]
Nakasone said the mission of MIST is to promote the science behind voice recognition.
[Updated at 9:55 a.m.]
West is asking Nakasone about a scientific group he works with that is trying to establish industry standards for voice analysis. Nakasone said he helped coordinate the working group, and this group is sponsored by the FBI. The acronym for the group is MIST.
[Updated at 9:52 a.m.]
Nakasone is discussing his experience, and his current work in the field of voice analysis.
[Updated at 9:49 a.m.]
Prosecutor Mantei has finished his direct examination of Nakasone, and now defense attorney Don West is asking him questions.
[Updated at 9:47 a.m.]
"We intentionally or unintentionally are recording the perceptual features of the person's voice. When he is speaking normally, slowly, excited, emotional, all of this is stored in the brain," said Nakasone.
[Updated at 9:43 a.m.]
Nakasone is explaining how a trained human ear can distinguish and analyze voices as well.
[Updated at 9:39 a.m.]
Nakasone said a person's pitch can change when screaming or under the duress of an extreme emotional state.
[Updated at 9:36 a.m.]
Prosecutor Mantei asked Nakasone to explain what pitch means. Nakasone said it is the perception of the vibration of the vocal cords.
[Updated at 9:33 a.m.]
Nakasone could not make a comparison or analysis in Zimmerman's case, because the sample quality was too poor.
[Updated at 9:31 a.m.]
Nakasone was able to isolate about a three-second sample of screaming from the 911 call.
[Updated at 9:29 a.m.]
"We cannot really analyze any voice which is stepped over by something else or superimposed with other people's voice," said Nakasone.
[Updated at 9:27 a.m.]
Nakasone received multiple voice samples in this case to analyze. One of the samples was the 911 call from the night of the shooting that has screams in the background.
[Updated at 9:24 a.m.]
Nakasone said the distance the microphone is away from the source of the voice has an impact on the quality on the sample.
[Updated at 9:21 a.m.]
The voice sample must be a certain length and quality in order to conduct a reliable voice analysis according to Nakasone.
[Updated at 9:19 a.m.]
Nakasone said the first step in voice analysis is to examine the quality of the sample or recording.
[Updated at 9:17 a.m.]
Prosecutor Rich Mantei has asked Nakasone to explain the methods people in his field use for voice analysis.
[Updated at 9:15 a.m.]
Nakasone has had 30 or 40 peer-reviewed articles published in a variety of industry publications.
[Updated at 9:13 a.m.]
Nakasone is talking about the research he has conducted in computer assisted voice analysis systems.
[Updated at 9:10 a.m.]
Nakasone is explaining his resume and education. He is a senior scientist for the FBI, and he conducts voice analysis for the bureau.
[Updated at 9:08 a.m.]
Prosecutors have called Dr. Hirotaka Nakasone to the stand. He testified as a defense voice analysis expert for the FBI during the Frye Hearing.
[Updated at 9:06 a.m.]
The attorneys are at a sidebar with the judge.
[Posted at 9:02 a.m. ET]
Zimmerman is in the courtroom. Judge Nelson is on the bench, and the jury is being seated.