(CBS/AP) --In a hearing Monday afternoon ahead of the George Zimmerman trial, a biometrics expert is reportedly expected to discredit findings of a state expert who heard Trayvon Martin begging in the background of a neighbor's 911 call placed the night of the deadly altercation.
Zimmerman, a former neighborhood watch captain, is accused of killing unarmed Florida teen Martin during a confrontation last year in a Sanford, Fla. gated community.
The testimony of James L. Wayman comes after a day of ongoing jury selection proceedings as the court once again takes up the issue of whether the jury, once seated, may hear testimony about the disputed 911 call.
A state expert claims that he heard Martin saying "I'm begging you" in the background of the call. Other experts, however, have testified that the quality of the tape was too poor to determine who was screaming. Wayman is also expected to testify that audio work done by the state's experts should not be trusted, the Orlando Sentinel reports.
Jury selection also continued Monday, and Circuit Judge Debra Nelson asked four more potential jurors to return for further questioning. Prosecutors and defense attorneys are seeking a pool of 40 potential jurors who have been screened for any influence of pretrial publicity before moving to a second round of questioning.
The number of potential jurors asked to return now stands at 32.
They must agree on six jurors and four alternates to hear the case.
Also on Monday, Nelson granted a defense request to keep jurors' personal information for a secret for a "cooling off" period after the trial, but decided to rule later on how long the time period would last.
Defense attorney Mark O'Mara said "at least three" potential jurors have been questioned with "significant concerns" over safety and maintaining anonymity.
Zimmerman is pleading not guilty in Martin's killing, saying he acted in self-defense.