Correction: An earlier version of this article

The boy in the dark-colored hooded sweatshirt straddled the man in red, doing a mixed-martial-arts-style “ground-and-pound.”

Or the boy in the hoodie was on the bottom, crying out for help.

Jurors will have to sort through those seemingly contradictory images, offered Thursday and Friday by neighbors who peered through the rain on the night that George Zimmerman fatally shot an unarmed African American teenager named Trayvon Martin in February 2012. The testimony is playing out in front of a capacity audience, drawn by the intense national attention sparked by allegations from civil rights leaders that Martin might have been targeted because of his race. Zimmerman, a neighborhood watch volunteer who was 28 at the time, has white and Hispanic parents.

In excruciating detail, prosecutors and defense attorneys have sought to establish who was on top and who was on the bottom in the seconds before Zimmerman pulled the trigger. Their positioning is critical because Zimmerman, the man in red that night, is claiming that he shot Martin, 17, in self-defense.

At first, neighbor Jonathan Good thought he was seeing a dog attack. But as he looked closer, he testified Friday, he saw two figures locked in “a tussle” in the grass near his townhouse in the Retreat at Twin Lakes gated community. The man on the bottom yelled, “Help,” Good told jurors.

The figures shifted to the concrete walkway, and that’s when Good says he saw the dark-clothed person — who he now knows was Martin — straddle the man in red. The figure on top was “raining down blows” and was using moves similar to a mixed martial arts (MMA) combatant, Good said.

Late Friday, the references to MMA took on a new complexity. A physician’s assistant who had treated Zimmerman testified that his medical notes show that Zimmerman had been practicing MMA and training “intensely” in hopes that the exercise would help him overcome difficulties sleeping.

But Good could not affirm a key defense claim: that Martin pounded Zimmerman’s head into the concrete walkway, producing the large bumps visible in photographs of the defendant shown to the jury.

Good’s testimony will be weighed against the memories of another neighbor, who testified Thursday that the man in red was on top during the struggle.

Selma Mora, a construction-equipment saleswoman who testified through a Spanish interpreter, said she heard a “soft” crying in pain. The figure in red was on top, she said. What she saw reminded her of a jockey riding a horse.

Jenna Lauer, another witness who testified Thursday, recalled a “surreal” scene, with “yelps” of pain morphing into screams for help. Those cries could be heard in the background of a chilling 911 call Lauer made. On that call, the gunshot that ended Martin’s life can be heard.