George Zimmerman's defense rested in his second-degree murder case on Wednesday, after calling 19 witnesses over the course of four days in court. The defense's case honed in on evidence and testimony to support its theory: Zimmerman was bloodied, beaten and crying out for help before he fired the shot that killed 17-year-old Trayvon Martin.

'Georgie's' voice

The defense did the unexpected Monday afternoon, calling Trayvon's father, Tracy Martin.

It was part of one of the trial's long debates: Whose voice did a 911 call capture calling out for help before the shooting?

The testimony came after two Sanford police investigators testified they'd asked Martin that question in the days after the shooting, and he replied the voice wasn't his son's.

Martin disputed that account: "I never said, 'no that's not my son's voice.'"

Said Zimmerman's friend and former co-worker Sonda Osterman: "Yes, definitely, it's Georgie." Her husband, Zimmerman's best friend, agreed.

Another former co-worker, Geri Russo: "My immediate reaction was, that's George's voice."

The defense's first witness was Zimmerman mother. Its last was his father. Both said the voice was their son's.

'Physically soft'

Jurors were presented an unflattering assessment of Zimmerman's physical abilities this week: Soft. Unathletic.

Days after testimony by a state witness that Zimmerman had been training in mixed-martial-arts, the defense called on Zimmerman's trainer to counter the notion that he was a capable fighter.

"He's just soft, physically soft," said Adam Pollock, of Kokopelli's Gym and Training Center in Longwood.

The trainer said Zimmerman started out at a 0.5 in grappling, advancing only to a 1 or 1.5 out of 10.

Later, the defense called on Dennis Root, a former law enforcement officer and trainer who testified as an expert on defensive use of force.

Based on the evidence and "the totality of [Zimmerman's] training background and experience," Zimmerman likely didn't have any other choice but to open fire, he testified.

'Severe force'

The state spent much of its case trying to convince jurors that Zimmerman's injuries were minor: Small, superficial cuts and abrasions, that don't match his account of the shooting or support he was in fear for his life.

The defense countered with a renowned expert: Forensic pathologist Dr. Vincent Di Maio, who said the beating Zimmerman described could killed him, if it hadn't stopped.

The two cuts to the back of Zimmerman's head, Di Maio said, indicate being struck against a hard surface with "severe force." Zimmerman would've been "at a minimum, stunned," he said, and further strikes could've led to brain swelling, internal bleeding and other critical damage.

"At some point, you're gonna die," he said.

Tension in court

By the end of a 13-hour court session Tuesday, defense attorney Don West was visibly exasperated, and later protested the early start time Circuit Judge Debra Nelson announced for Wednesday.

"Judge, I'm not physically able to keep up this pace much longer," West said. Nelson began walking off the bench, as he continued: "We've had full days every day. Weekends, depositions at night."

The judge later pushed Wednesday's court session back to its normal time.

The tension continued when Nelson attempted to question Zimmerman — over repeated objections by West — on whether the defendant had decided if he was going to testify.

"I object to the court inquiring of Mr. Zimmerman as to his decision about whether or not to testify," West began.

Interjected Nelson, forcefully: "Your objection is overruled."