Jose Baez of Casey Anthony Fame to Represent Lead Investigator in George Zimmerman's Murder Trial

Nov. 20, 2012— -- In an unusual move, the lead detective in George Zimmerman's murder trial, has hired Jose Baez, who gained fame when he successfully defended Casey Anthony against charges that she'd murdered her 2-year-old daughter, to represent him.

Chris Serino, a former Sanford, Fla., police major crimes investigator, ignited controversy when he filed an arrest affidavit weeks after the shooting death of Trayvon Martin, despite insufficient evidence to make a case.

Baez, whose name had already popped up as a possible attorney to represent Zimmerman, confirmed to ABC News that he would now represent the controversial investigator Serino as depositions get under way.

Serino was reassigned to the overnight shift soon after video and audio interrogation tapes were released last summer that revealed he had doubts about Zimmerman's version of events in the fatal shooting of 17-year-old unarmed teenager Trayvon Martin last Feb. 26.

Zimmerman, a former neighborhood watch captain, said Martin was acting suspicious and soon became confrontational when Zimmerman encountered him walking through the subdivision where Zimmerman lived. In audio tapes recorded three days after the shooting, Zimmerman claimed he was attacked by Martin and shot him in self-defense.

But in the Feb. 29 recordings, Serino openly doubted the story.

"You ever hear of Murphy's Law," asks Serino. "This person was not doing anything bad. You know the name of the person that died?"

"Tavon," responds Zimmerman."Trayvon," Serino shot back."Trayvon Martin" responds Zimmerman."Trayvon Benjamin Martin. ... He was 17. ... A kid with a future," said Serino. "In his possession we found a can of ice tea and a bag of Skittles. And $40 in cash. Not the goon."

Serino then questioned the extent of Zimmerman's injuries, telling him that despite the broken nose and two lacerations on the back of his head, his injuries did not seem consistent with someone involved in a life-or-death struggle.

"You wanted to catch him. You wanted to catch the bad guy," said Serino, aggressively.

Serino later recommended that manslaughter charges be brought against Zimmerman, but Seminole County State's Attorney Norm Wolfinger rejected the request, citing a lack of concrete evidence. The initial lack of an arrest in the case led to widespread protests, and propelled the case into the national headlines. In April, special prosecutor Angela Corey, appointed by Florida Gov. Rick Scott, charged Zimmerman with second-degree murder.

Serino and several other Sanford police officers will soon be giving sworn statements to the Zimmerman legal team. Mark O'Mara, Zimmerman's lead attorney, said that public pressure -- not evidence -- helped lead to charges being filed in the case.

The Zimmerman defense team is building evidence for an immunity hearing at which they'll likely invoke Florida's "Stand Your Ground" self-defense law, and argue that Zimmerman killed Martin in self-defense. If the case is not dismissed, the trial is set for June 10.