Who was on top in Zimmerman-Martin tussle? Witness testimony in conflict.

A neighbor of George Zimmerman testified in Mr. Zimmerman’s murder trial Friday that it appeared Trayvon Martin was straddling and striking Zimmerman before the unarmed teenager was shot.

The neighbor, Jonathan Good, said he went outside after hearing a noise outside his town house on Feb. 26, 2012. Mr. Good said he saw what looked like a “tussle” when he stepped onto his back patio.

“What’s going on? Stop it,” Good said he yelled.

Good returned inside to call 911 and was on the phone with police when he heard a gunshot.

However, Good said he did not see anyone's head being slammed into the concrete sidewalk, which Zimmerman's lawyers say Trayvon did to him. Good initially testified that it appeared "there were strikes being thrown, punches being thrown," but during detailed questioning, he said he saw only "downward" arm movements being made.

Good, who lived in the same gated community in Sanford, Fla., as Zimmerman, was the fourth neighbor who partially witnessed the death of Trayvon to testify in the trial, Reuters notes.

“Each has given slightly different accounts,” Reuters notes.

Good's testimony complicates the picture for jurors after two other neighbors testified Thursday that they believed Zimmerman was on top. But unlike Good, those neighbors did not see the fight before the gunshot was fired.

Neighbor Selma Mora testified Thursday "that after she heard what she now believes was a gunshot, she rushed outside and saw the man who survived the fight on his knees straddling Trayvon," according to The Orlando Sentinel. "That man then stood up and began pacing, she said.” 

Jennifer Lauer, a former neighbor of Zimmerman, testified that she heard yelps for help outside her town home on the night Trayvon was shot, but couldn't tell who was screaming.

“Lauer testified she heard an exchange that was presumably between two people. She then heard a scuffling, ‘like sneakers on pavement and grass,’ ” CBS News reported Thursday.

"It kinda sounded like wrestling," Ms. Lauer said. "At one point I felt like they were going to come through the screen."

Another neighbor, Jayne Surdyka, testified Wednesday that during the struggle, she saw a person in dark clothes on top of the other person. Trayvon was wearing a dark sweat shirt, and Zimmerman wore red clothing.

Ms. Surdyka said she heard cries for help and then multiple gunshots: "pop, pop, pop." However, only one shot was fired in the fatal encounter.

"I truly believe the second yell for help was a yelp," said Surdyka, who later dabbed away tears as prosecutors played her 911 call. "It was excruciating. I really felt it was a boy's voice."

On Friday, Good said he thought the person on the bottom yelled for help, but later acknowledged he was not 100 percent sure, according to Fox News. It was his opinion, he said, that Zimmerman was the one calling for help.

Good also testified that he saw a person in black clothing on top of another person with "white or red" clothing. He said he couldn't see faces but it looked like the person on the bottom had lighter skin. Trayvon was black, while Zimmerman identifies as Hispanic and was wearing a red jacket. 

Zimmerman, who has pleaded not guilty, is on trial for second-degree murder for the February 2012 shooting death of Trayvon, 17. Zimmerman's lawyers have said he acted in self-defense after he was attacked.

Under Florida law, all six jurors must be convinced Zimmerman acted with “ill will,” “hatred,” or “an indifference to human life,” notes Reuters.

• Material from the Associated Press was used in this report.