(CNN) -- Jury selection in George Zimmerman's trial in Seminole County, Florida, dragged into its third day Wednesday, with one potential juror saying he couldn't keep an open mind about the case.
Zimmerman, a former neighborhood watch volunteer, is charged with second-degree murder in the death of Trayvon Martin on February 26, 2012. He claims he shot the teenager in self-defense.
Attorneys for both sides continued to grill candidates for the jury about their knowledge of the case, based on publicity.
Zimmerman participated in the process again Wednesday by taking notes and occasionally chatting with his attorneys. He even laughed a few times during some of the lighter moments of the proceeding. Zimmerman chuckled when a potential juror said she had seen defense attorney Mark O'Mara on television, but had no idea what he'd said.
One candidate, a white male who appears to be in his 20s, said he didn't think it was possible for him to block what he has already heard about the case from his mind and listen to the judge's instructions.
"Murder is murder, even if self-defense. It doesn't make it right to kill somebody," the potential juror said.
Each potential juror questioned so far in the case has admitted to hearing about the case in some way. However, the potential jurors' understanding of the case varies widely.
Some of them can recall small details, such as that Martin was on the phone with his girlfriend when Zimmerman allegedly confronted him, but another juror said he has very limited knowledge of the case.
"Some altercation happened. How did he die? I don't know," the potential juror said.
A representative for the court has told HLN that once 30 jurors have been questioned about media coverage and have not been eliminated for cause, the next stage for these potential jurors will be traditional voir dire, in which attorneys will be able ask them questions about other subjects they believe to be important to the case.
These subjects could include race, self-defense and crime.
The court only needs 10 more jurors to move on to voir dire, meaning 20 have qualified. Four jurors questioned Wednesday were dismissed.