Jurors in the George Zimmerman murder trial watched a video of the neighborhood watch volunteer re-enacting his scuffle with Trayvon Martin for a Sanford Police detective on the day after the deadly shooting.

Prosecutors played the video Monday while lead detective Chris Serino was on the witness stand.

Follow LIVE UPDATES from Monday's testimony.

Monday's testimony

  • Chris Serino, a Sanford Police detective who investigated the shooting.
  • Doris Singleton, Sanford police officer who took Zimmerman's statement after the shooting.
  • Dr. Hirotaka Nakasone, an FBI audio analysis expert.

Chris Serino was the lead detective assigned to the Trayvon Martin shooting.

Serino said when he met with officers as he arrived at the scene of the shooting, the body of Trayvon Martin had not yet been identified. He then went to the police station around midnight and made contact with Zimmerman.

Zimmerman accompanied Serino back to the scene the day after to have him re-enact the events surrounding the shooting.

In an interview several days later, Serino asked Zimmerman several pointed questions, suggesting Zimmerman was running after Martin before the confrontation.

Serino and Singleton also asked Zimmerman why he didn't explain to Martin why he was following him. The officers insinuated that Martin may have been "creeped out" by being followed.

"Do you think he was scared?" Singleton asked Zimmerman in one video interview.

Under cross-examination, though, Serino said Zimmerman seemed straightforward in his answers and didn't show any anger when talking about Martin. Serino said the increasingly pointed questioning was a tactic known as a "challenge interview" where detectives try to break someone's story to make sure they're telling the truth.

Defense attorney Mark O'Mara pointed out Serino saying he would have to speak for Zimmerman, and he would be under a lot of scrutiny. 

"In this particular case, he could have been considered a victim, also," Serino said, adding he was keeping an open mind, but there were external concerns he needed to get clarified.

Doris Singleton is a Sanford police officer who took George Zimmerman's statement immediately after he shot Trayvon Martin.

Singleton said she interviewed Zimmerman to get his statement about what happened. Prosecutors played the interview for the jury Monday.

Zimmerman said he saw Martin walking through his neighborhood on a dark, rainy night while Zimmerman was driving to the grocery store. He told Officer Doris Singleton that he didn't recognize Martin, and that there had been recent break-ins at his townhome complex.

"These guys always get away," Zimmerman told Singleton, a statement similar to one that prosecutors have used previously to try to show that Zimmerman was increasingly frustrated with the burglaries and his encounter with Martin was a breaking point.

Zimmerman told the police officer that he lost track of Martin and got out of his truck to look for a street name he could relay to police dispatcher. When the dispatcher suggested Zimmerman didn't need to follow Martin, Zimmerman started to head back to his vehicle. At that point, Zimmerman said Martin jumped out of some bushes, punched him and he fell to the ground.

Zimmerman said that Martin began hitting his head against the sidewalk as Zimmerman yelled for help and that Martin told him, "You're going to die tonight."

With Zimmerman's shirt and jacket pushed up during the struggle and his holstered gun now visibile, he thought Martin was reaching for his firearm holstered around his waist. Zimmerman told the officer that he shot Martin and the teen said, "You got me."

In a written statement, Singleton read in court, Zimmerman refers to Martin as "the suspect." Singleton testified that neither she, nor Zimmerman knew the teen's name at that point.

Singleton also recounted that Zimmerman noticed a cross she was wearing and asked her if she was Catholic, telling her, "In the Catholic religion, it's always wrong to kill someone."

The officer responded, "If what you're telling me is true, I don't think that what God meant was that you couldn't save your own life."

Zimmerman also acted surprised when Singleton told him Martin had died.

"He's dead?!" Singleton recalled Zimmerman saying, before he lowered his head toward the table in the interrogation room.

When asked by defense attorney Mark O'Mara whether Zimmerman showed any anger or ill will in talking about Martin, the officer said, "No."

Prosecutors must show that Zimmerman acted with ill will or a depraved mind in order to get a second- degree murder conviction.

Dr. Hirotaka Nakasone is an audio analysis expert for the FBI.

Prosecutors called Dr. Nakasone to focus on the issue of who was screaming for help on 911 calls during the confrontation. Jurors were played the 911 calls several times last week.

The recordings are crucial pieces of evidence, because they could determine who the aggressor was in the confrontation. Martin's family contends it was the teen screaming, while Zimmerman's father has said it was his son.

Even though he was a pre-trial witness for the defense, prosecutors called Nakasone to set up later testimony from either the teen's mother or father that they believe it was their son yelling for help.

During his pre-trial testimony, Nakasone testified that there wasn't enough clear sound to determine whether Zimmerman or Martin was screaming on the best 911 sample, an assertion he repeated Monday.

"It's not fit for the purpose of voice comparison," Nakasone said.

Nakasone also said guessing a person's age by voice is "complicated" in general, and it was impossible to determine with the 911 sample he heard.

The FBI expert said that it's easier for a person with a familiarity of a voice to identify it than someone who has never heard it previously. That is especially true if the recording is of a subject screaming and the person trying to identify the voice has heard the subject under similarly stressful circumstances previously, Nakasone said.

But under cross-examination by defense attorney Don West, Nakasone said there was a risk of increased listener bias if people trying to identify a voice are listening to a sample in a group, as Martin's parents did, rather than individually.

"There might be a risk of bias included in the end results," Nakasone said.

Nakasone's pretrial testimony, along with other defense experts, helped keep two prosecution audio experts from testifying. One prosecution expert ruled out that it was Zimmerman screaming on the 911 call and the other thought it was the teen.

Judge Debra Nelson ruled that the methods used by the experts aren't reliable.

2nd week of testimony begins

More than 20 witnesses last week testified during the opening week of a testimony in a trial that has opened up national debates about race, equal justice, self-defense and gun control.

Zimmerman has said he fatally shot the teen in February 2012 in self-defense as the Miami-area black teenager was banging his head into the concrete sidewalk behind the townhomes in a gated community. Zimmerman is charged with second-degree murder and has pleaded not guilty.

Zimmerman, 29, could get life in prison if convicted of second-degree murder. The state argued during its opening statement that Zimmerman profiled and followed Martin in his truck and called a police dispatch number before he and the teen got into a fight.

Zimmerman has denied the confrontation had anything to do with race, as Martin's family and their supporters have claimed.