By the time they stepped down from the witness stand, both had been damaged.
The first was Jayne Surdyka, a former Olympic-caliber marathoner. Just minutes before the shooting, she heard someone make two desperate cries for help — the second she described as a "yelp."
She is convinced, she said, that the second voice was Trayvon's.
"Someone sounded very angry, very agitated," she said. The other person spoke with "a lighter, softer, higher-pitched voice."
She also reported seeing two figures on the ground fighting or wrestling.
But her account does not mesh with other evidence on three key points.
She testified that Trayvon was on the bottom, facedown when Zimmerman shot him. But Trayvon was shot at near-point-blank range in the chest — not the back.
Surdyka said she heard three gunshots. There was one.
She also got their clothing confused, saying the figure wearing black clothing survived, and she saw him stand up and walk around after the shooting.
Trayvon was wearing a charcoal-colored hoodie, Zimmerman a red jacket.
The second neighbor, Jeannee Manalo, also had credibility problems. She testified that she heard "a howling sound," looked out a glass door and saw two figures on the ground fighting.
The one on top was moving his hands "like he's hitting him," she said.
"That's when my husband told me to sit down and mind my own business," she said.
A few seconds later, she heard a shot, she said.
When she was interviewed immediately after the shooting, she told police she could not tell who was on top, but a few weeks later, after seeing photos of Trayvon on television, she told investigators that she was convinced it was Zimmerman because he is bigger.
On Wednesday, that was her testimony again until defense attorney Mark O'Mara pointed out that the photos of Trayvon on which she had relied showed him at about age 10 to 12.
"You're not sure as you sit here today who was where in the altercation?" O'Mara asked.
"No," she answered.
Also Wednesday, jurors listened as prosecutors played recordings of five calls Zimmerman made to police dispatchers in the months before the shooting.
In four he was reporting suspicious people. In each of those cases, the subject was black.