By Barbara Liston
SANFORD, Florida (Reuters) - A forensic expert backed George Zimmerman's account of his fatal shooting of Trayvon Martin on Tuesday, testifying in the neighborhood watchman's murder trial that evidence showed he was under the unarmed black teenager when he fired his gun.
The forensic pathologist testifying for the defense cited the trajectory of the bullet that pierced Martin's chest and gun powder on his body in supporting Zimmerman's version of events of the shooting, in a setback to the prosecution.
"It's consistent with somebody leaning over the person doing the shooting," said Dr. Vincent DiMaio, a former chief medical examiner in Texas, in testimony in a case that inspired renewed national debate on race, profiling, gun rights and self defense.
It was the latest in a series of blows to the prosecution, underscoring a widely held view among lawyers following the case that the state aimed too high in charging Zimmerman with murder.
Zimmerman remained free for 45 days after the February 26, 2012, killing because police initially declined to arrest him, accepting his claim he shot and killed the 17-year-old Martin in self-defense.
A special prosecutor brought the charge of second-degree murder against Zimmerman, possibly bowing to public pressure, after protests and cries of injustice in Sanford, the small Florida city where the incident occurred, and several major U.S. cities.
DiMaio testified that Martin could have been conscious and able to move for five to 10 seconds after he was shot through the heart, based on the typical reserve oxygen in the brain.
That testimony appeared to bolster Zimmerman's overall credibility and his claim that he placed Martin's arms out to the side after shooting him, despite a photograph taken of Martin after he died that showed his arms under his body.
Prosecutors wrapped up their case against Zimmerman on Friday after nine days of witness testimony. Lead defense attorney Mark O'Mara said he hopes to rest by Wednesday.
That means the case could go to the jury by this weekend. It is still unclear whether Zimmerman will testify in his own defense.
Lawyers caution that no one knows the single piece of evidence or witness statement that could lead to a conviction or acquittal. But O'Mara certainly seems to have the upper hand as the case heads into closing arguments.
"The trial is not over," said David Weinstein, a former prosecutor and Miami-area defense attorney who is not involved in the case. "However, from where things stand right now, a conviction does not appear likely."
The former neighborhood watch volunteer faces up to life in prison if convicted of second-degree murder, although either side can request that the jury also consider the lesser offense of manslaughter, with a maximum penalty of 30 years.
In a setback for the prosecution on Monday, Seminole County Circuit Judge Debra Nelson ruled that defense lawyers could introduce evidence that Martin had the active ingredient of marijuana in his system when he was killed.
After lengthy debate, Nelson said she would rule on Wednesday whether jurors should see a digital reconstruction of the crime scene in a gated community in Sanford.
DiMaio testified that Zimmerman, 29, had at least six injuries after his clash with Martin - including two on the back of his head that appeared to indicate impacts with concrete - one on each temple, one on his forehead and one on his nose.
Valerie Rao, a medical examiner who testified last week for the prosecution, said Zimmerman suffered "insignificant" injuries in the incident, as the state attempted to undermine Zimmerman's claim he feared for his life.
DiMaio said the injuries could be worse than they appeared. Lacerations to Zimmerman's head suggested the use of "severe force," he said, lending credence to his claim that Martin slammed Zimmerman's head into a concrete walkway after knocking him to the ground with a punch that broke his nose.
Once a verdict is rendered, it seems likely that many Americans will be disappointed however Zimmerman's fate is decided, because the killing and the trial have attracted wide national attention.
As a result, some authorities are preparing for possible racial tensions. The Broward County Sheriff's Office, the state's largest, said on Monday it was working closely with the Sanford Police Department and other local law enforcement agencies to coordinate "a response plan in anticipation of the verdict."
Sanford's population of 54,000 is about 30 percent black.
"We don't have information about a specific event that might take place at the conclusion of the trial, but we encourage everyone to keep any protests peaceful," Broward Sheriff Scott Israel said in a statement.
(Additional reporting by Kevin Gray in Miami, Writing by Tom Brown; Editing by Dina Kyriakidou, Paul Thomasch, Steve Orlofsky and Philip Barbara)