SANFORD, FL - JULY 11: Defendant George Zimmerman arrives for his murder trial in Semimole circuit court July 10, 2013 in Sanford, Florida. Judge Debra Nelson has ruled that the jury can also consider a manslaughter charge along with the second-degree murder charge in the shooting death of Trayvon Martin. (Photo by Gary W. Green-Pool/Getty Images)
Authorities said Zimmerman did not return fire. He flagged down a local officer about the same time Apperson called 911, authorities said in a news conference on Monday.
"I was coming back from lunch and a guy was screaming out his window, 'Please call 911. Please call 911," said witness Kenneth Cornell. "He's like, 'I shot George Zimmerman. Please call 911. I need someone to call.'"
Cornell said the man identified himself as Apperson and told him he didn't have a cellphone and that this was the third incident between him and Zimmerman.
"He said this is the third incident. They've been going back and forth for the last three months," said Cornell.
Authorities said they still don't know what led to the shooting.
Attorney Mark NeJame, who was an analyst for networks during Zimmerman's murder trial, is representing Apperson. So far, no arrests have been made, and no charges have been filed.
Police towed Zimmerman's truck, which appears to have a bullet hole in the passenger-side window, to the Lake Mary Police Department. A second vehicle was later hauled away.
"I was working in the back yard and I heard the shots, and I said, 'That sounded like gunshots,'" said witness George Paschek. "I heard two (shots). I didn't hear no crashes, cars hitting each other or anything like that."
In the September incident, Zimmerman was questioned after he and Apperson allegedly got into a shouting match on Lake Mary Boulevard. Apperson told police he didn't want to press charges despite claiming Zimmerman showed up at his workplace two days later threatening to kill him.
WFTV looked into Apperson's history with law enforcement and learned he's been arrested at least six times in Seminole County, twice for drug possession in 1995 and 1998, twice for DUI in 2000 and once for trespassing.
Following another domestic confrontation, he was arrested on charges of aggravated assault, battery and criminal mischief after his then-girlfriend said he pointed a gun at her face during an argument, smashed her coffee table and pushed her out of the house they shared. Samantha Scheibe decided not to cooperate with detectives, and prosecutors didn't pursue the case.
Zimmerman was accused by his estranged wife of smashing an iPad during an argument at the home they had shared. Shellie Zimmerman initially told a dispatcher her husband had a gun, though she later said he was unarmed. No charges were filed because of a lack of evidence. The dispute occurred days after Shellie Zimmerman filed divorce papers.
Last September, a driver said Zimmerman threatened to kill him, asking "Do you know who I am?" during a road confrontation in their vehicles. The driver decided not to pursue charges, and police officers were unable to move forward without a car tag identified or witnesses.