A witness told police that, after the gunshot, she saw a "larger" man standing over Martin.
Police who arrived described the shooter, Zimmerman, as compliant in answering their questions and willingly putting on handcuffs.
He had blood on his nose -- with one officer saying it appeared "broken," while noting "swelling" of his face -- and, as photographs showed, blood on the back of his head. His back was wet and soiled, as if he'd been in grass.
Zimmerman claimed that Martin had attacked him, hitting him in the nose and knocking him back into the pavement. It was only then, in self-defense, that he'd taken out his gun and shot the teen, he said.
Tests, the results of which were made public Thursday, would show evidence of Zimmerman's hands on the firearm, but not Martin's. An analysis of scrapings from underneath the teenager's fingernails did not contain any of Zimmerman's DNA, as might rub off in the case of a prolonged struggle.
At the scene, Zimmerman declined to be transported to the hospital despite his apparent injuries.
A police officer reiterated that offer after Zimmerman complained his head hurt and he felt lightheaded while being driven to the Sanford Police Department. But again he turned it down.
While at the police station, Zimmerman requested some tissues, water and to go to the bathroom, but little else. He ended up turning over his clothes to police but, after being questioned and putting on a change of clothes brought in by his wife, he headed home.
Tracy Martin, meanwhile, didn't know where his son was. He filed a missing person's complaint on the morning of February 27, telling authorities that his son hadn't returned from going to the store the previous evening.
Police then showed Tracy Martin a picture taken from the crime scene, and he confirmed the dead teenager was, in fact, Trayvon.
As to Zimmerman, he remained in limbo for weeks.
Police had declined to arrest him that night, saying there wasn't enough evidence to refute his self-defense claim.
But the investigation continued. In a capias request, a request that someone be taken into custody, on March 13, police described what happened as "ultimately avoidable by Zimmerman, if Zimmerman had remained in his vehicle and awaited the arrival of law enforcement, or conversely if he had identified himself to Martin as a concerned citizen and initiated dialog (sic) in an effort to dispel each party's concern.
"There is no indication that Trayvon Martin was involved in any criminal activity."
On April 11, special prosecutor Angela Corey announced that Zimmerman was being charged with second-degree murder.
He was subsequently arrested and, eventually, released on bail. The start of his scheduled trial has not yet been set.