SANFORD - Two days after his son Trayvon had been shot, Tracy Martin wanted answers about why the killer, George Zimmerman, had not been arrested.
So Tracy Martin went to the Sanford Police Department and met with investigators.
Lead detective Chris Serino played for Martin a 911 call a neighbor had made. Audible in the background were screams and a gunshot.
Is that your son's voice, Serino asked, according to three witnesses who testified Monday.
"He looked away and under his voice said, 'No,'" Serino told jurors.
Another Sanford police investigator, Doris Singleton, backed up that account.
"He was very upset. He was very sad. He hung his head and cried," Singleton said. "I was choked up myself. ... I felt horrible for him."
Tracy Martin, however, told jurors Monday that that's not what he said that day.
"I never said that's not my son's voice," Martin testified. I said I could not be certain, he said.
After listening to the recordings back-to-back about 20 times three weeks later, he was certain that it is Trayvon's voice, he said.
Why did you listen to it so many times, asked Assistant State Attorney Bernie de la Rionda.
"I was just trying to figure out the night of Feb. 26, 2012 — why did the defendant get out of his vehicle and chase my son," Martin said.
Tracy Martin's 20 minutes on the witness stand was one of the highlights of Day 20 of Zimmerman's second-degree murder trial, which could conclude this week.
Zimmerman is the Neighborhood Watch volunteer who killed Trayvon Martin, an unarmed black 17-year-old from Miami Gardens, in what he told police was a case of self-defense.
Several of Zimmerman's Sanford neighbors have testified that they saw and heard portions of the fight, but no one saw it how it started. One neighbor, John Good, testified that he saw Trayvon on top of Zimmerman, hitting or pushing him down.
The state suffered a major defeat Monday when Circuit Judge Debra S. Nelson ruled that defense attorneys may tell jurors that Trayvon had a small amount of marijuana in his system at the time of his death.
Assistant State Attorney John Guy had argued that that was a "backdoor" attack on Trayvon's character.
But defense attorney Don West argued that a defense expert will tell jurors that the amount was enough to create "some level of impairment."
Also, the medical examiner who performed Trayvon's autopsy, Shiping Bao, testified Friday that the amount may have had an impact on his behavior.
Also on Monday,