SANFORD, Fla. -

The jury on Tuesday heard testimony from a state medical examiner expert who called George Zimmerman's injuries minor.

[Chat recap: Tony Pipitone inside courtroom]

Zimmerman, 29, is charged with shooting and killing 17-year-old Trayvon Martin in Sanford.

Dr. Valerie Rao examined Zimmerman's reenactment video, 36 photos, medical history/record, police video, autopsy reports and police reports. Rao did not do the autopsy on Martin.

Prosecutor John Guy asked Rao about Zimmerman's injuries, which she called "not life-threatening" and "very insignificant." She said Zimmerman's head injuries are consistent with hitting concrete but only one strike. Rao said the injuries were not consistent with being repeatedly "slammed" against the concrete since the injuries aren't great-force injuries.

"They were so minor that the individual who treated and examined Mr. Zimmerman decided stitches weren't required," Rao said.

Defense attorney and former Local 6 legal analyst Mark O'Mara questioned Rao in cross-examination about how Special Prosecutor Angela Corey appointed Rao to the medical examiner position.

O'Mara asked Rao if she was suggested Martin only hit Zimmerman once. Rao said she's not suggesting it was only one hit to the nose, but could be one. She then says it could be two, three or four depending on the force/impact.

O'Mara asked if Rao found any injuries in Martin's autopsy reports, to which she said she didn't see any noted, although she didn't do the autopsy herself. Rao also added the facial injury could also be consistent with overhead blow, similar to what witness John Good described.

Rao did not identify bruising on Zimmerman's head, despite O'Mara's efforts, but then found one on the right side. O'Mara then described various scenarios and asked Rao what the injuries would be.

O'Mara then got Rao to expand her "3 impacts" of Zimmerman's head on cement to many more. He asked Rao "what about the next injury?" in hopes to drive home point injuries could have become life-threatening.

The defense objected to the state's next witness, Professor Carter, who would testify about the course Zimmerman took 1-2 years before shooting that included self-defense law instruction. Zimmerman had denied previous knowledge about self-defense law.

The state also wants to show Zimmerman had such interest in law enforcement that was his state of mind at the time of the incident. State prosecutor Richard Mantei said Zimmerman's behavior was an ongoing pattern, including applying and being rejected as law enforcement officer in Virginia and an application to ride around with Sanford police officers.

The state said Carter will expound on written materials to say "stand your ground" was taught in class Zimmerman took.

O'Mara said Zimmerman's schooling is unrelated to the case. Judge Debra S. Nelson said the state wants to show Zimmerman's knowledge of law, investigations and interviews. O'Mara said the "state can't create evidence" to have the professor impeach Zimmerman on it.

"That's their theory of the case," Nelson said, that Zimmerman "understood (the law enforcement) process." The defense sought proffer from state and Nelson gave defense a 30-minute recess to find case law to support their objection.

Nelson wanted to move on to the new witness and deal with the college course/records at 8:30 a.m. on Wednesday.

The state called one last quick witness on Tuesday, Kristen Benson, a Seminole County Sheriff fingerprint examiner. The jury was then dismissed as the court discussed outstanding issues.

The jury also heard on Tuesday Zimmerman's TV interview with Sean Hannity as Zimmerman said he has no regrets about shooting and killing Martin and felt as "it was all God's plan."

In the July 2012 interview with Fox News' "The Sean Hannity Show," Zimmerman said he had never heard of "stand your ground" before the shooting, to which the state claims it has evidence that statement is false.

In his first public interview since the shooting, Zimmerman also discussed how Martin was "trying to intimidate" him by implying he had a weapon and that Martin wasn't running out of fear but "skipping."

Zimmerman said Martin confronted him 30 seconds after he was heading back toward his truck and told Hannity about Martin's attack.

"I thought I'd lose consciousness. I didn't know what would happen at that point," Zimmerman said, describing when his head was hitting the concrete. "After he couldn't hit my head on concrete anymore, he tried to suffocate me, I kept pushing his hands off my mouth, nose."

He then tells Hannity the screams were definitely his.

The first testimony on Tuesday morning came from the lead police detective who investigated Martin's fatal shooting last year. Chris Serino returned to the witness stand, minutes after the judge ruled one of his statements from Monday's testimony be stricken from court record.

Serino testified for a second day Tuesday about his investigation into the fatal shooting of the 17-year-old Miami teenager by George Zimmerman, a neighborhood watch volunteer.

O'Mara played the part of the interview where Zimmerman says the screams in the background of the 911 call "don't even sound like me." The defense says he didn't mean it was not him screaming, it just sounded unlike him.

Serino told O'Mara it didn't concern him that Zimmerman made that statement.

The state then objected to the defense bringing in Serino's meeting with Martin's father, Tracy Martin, saying it was beyond the scope of direct questioning. Nelson sustained the state's objection and O'Mara said the defense will call Serino as a defense witness and will ask about Tracy Martin's interview with him not recognizing his son's screams.

During redirect, de la Rionda played the non-emergency phone call where Zimmerman says "these a******* always get away" and "f****** punks" in an effort to show Zimmerman had ill-will, spite or anger. Serino said it didn't show ill will or spite, but then changed his answer and agreed to a point.

The state then played Zimmerman saying in one of his interviews that his wife "got scared" after their neighbor was burglarized so he started the Neighborhood Watch program.

"These guys always get away," Zimmerman said in the interview. De la Rionda asked Serino if it was "accurate he (Zimmerman) is profiling Trayvon Martin as a criminal?" The defense objected and Nelson sustained the objection.

Serino said there was no evidence Martin was committing a crime or was armed. In the recording of the interview, Zimmerman says he was "going in the same direction" as Martin. Serino says that's "following."

"You wanted to catch the bad guy, f****** punk kid, right?" Serino said in the audio interview to a subdued Zimmerman.

The state pointed out discrepancies in Zimmerman's recollections in what the non-emergency dispatcher asked him to do and why he walked behind the condos. De la Rionda replayed the video of Zimmerman, claiming to look for address, then shows the photo of the address on the townhome in front of him. De la Rionda pointed out the street name Zimmerman claimed not to know is the same street used to enter the subdivision, to which Serino agreed. Zimmerman told investigators he didn't know the street name attached to the numerical address seen where he left his vehicle.

De la Rionda then asked Serino about Zimmerman's claim he stretched out the arms of Martin, despite the first picture of Martin's body showing Martin's hands under his torso. Serino called Zimmerman's claim inconsistent with first photo.

The state also noted Serino had no DNA, ballistics, statement from Jeantel when he challenged Zimmerman in an interview.

During re-cross, O'Mara asked Serino if he had said the word "a*******" before and how Zimmerman said it in his interview, which Serino said didn't cause him any concern. Serino agreed with O'Mara that Zimmerman didn't "screech" words as de la Rionda did during his redirect of Serino.

O'Mara then asked about a "slim jim," which is used to break into vehicles, being found near the shooting scene. Serino said the burglary tool was found in the bushes behind one the witness' residence where Zimmerman says Martin may have hid, but it was not tied to the shooting case.

O'Mara asked Serino if he thought Zimmerman was following Martin and had Serino admit following someone is not illegal. Serino said he thinks Zimmerman was just outside his vehicle when he was told not to follow Martin, but Zimmerman's call suggests otherwise.

"In totality of the whole thing ... George Zimmerman was trying to do something int he same direction Trayvon Martin was going," Serino told O'Mara.

Serino agreed with O'Mara that Zimmerman had grounds to call non-emergency line about Martin, but Serino wouldn't have questioned the teen himself. He also said Zimmerman seemed "elated" that someone might have video of his encounter with Martin.

During re-redirect, de la Rionda asks, "are you saying ... it's against the law for someone to wear a hoodie at night?" The defense objected and de la Rionda rephrased his question. De la Rionda also reinforced with Serino that the "slim jim" found the bushes had nothing to do with the case.

Nelson then limited O'Mara's re-recross to five minutes. O'Mara suggested the lack of blood on Martin's hands explained because it was falling toward the earth or backing up into nose.

The state's next witness was Mark Osterman, neighbor/friend of Zimmerman. Osterman wrote a book trying to defend "the best friend I ever had." Osterman, a federal air marshal, looked directly at the jury as he testified, like law enforcement officers are trained to do.

Osterman quoted Zimmerman saying, "somehow I broke his grip on the gun when the guy grabbed between the grip and hammer." Zimmerman had previously only told police Martin reached for the gun, not that he actually grabbed it.

"I thought he had said he grabbed the gun," Osterman said. "I believe he said he grabbed the gun."

Osterman said Zimmerman "either broke contact or knocked Martin's hand away" from gun before pulling and firing it.

Osterman said he believes anyone who is not a convicted felon should have a firearm and said he encouraged Zimmerman to get a gun.

"Police are not always there," Osterman said. Osterman then described Zimmerman as "stunned, wide-eyed .. detached ... he wasn't answering questions ... just wanted to go home."

During cross-examination, the defense tried to have Osterman say the screams on the 911 calls were Zimmerman. Nelson said it was beyond the scope of the state's direct questioning.

At the start of court on Tuesday, the state sought to bolster or widen its already-granted motion preventing police from giving opinion testimony about the Zimmerman investigation. Judge Debra S. Nelson allowed Serino and Detective Doris Singleton to say they saw no evidence of ill-will, spite, or hatred in court on Monday--all of which are elements of second-degree murder.

De la Rionda introduced case law to the motion, which would limit what police can say about their interpretation of the law. The state wants Serino's opinion struck from the court record.

Serino said on Monday that Zimmerman was telling the truth or was a pathological liar. In cross-examination, defense attorney and former Local 6 legal analyst Mark O'Mara got Serino to exclude being a pathological liar, leaving the truth.

Nelson did say during testimony on Monday that the defense was coming close to violating the granted motion to exclude police opinion about self-defense.

The defense said cases that limit police opinion on veracity apply to authorities attacking the defendant and that Zimmerman's case involves authorities supporting Zimmerman. The cases the state is citing say veracity and credibility are "province of the jury" and allowing witnesses to offer such opinions cause reversible error.

O'Mara asked for time to research the case law. The state said it's also entitled to a fair trial and that the court has barred opinion testimony, so the jury should be asked to disregard improper comment of Serino.

Nelson ruled in favor of the state and asked the jury to disregard the testimony that Serino believed Zimmerman's story.

"That was an improper comment as to truth of veracity of another witness. You are asked to disregard question and answer," Nelson said.

Also before the jury entered the courtroom on Tuesday, the state said the defense failed to attend a Seminole State College witness testimony last week outside of court. Nelson allowed the witness, who taught an online course, to testify outside of court because of a scheduling issue.

The state said the defense's failure to attend the testimony is a waiver of defense's right to cross-examine the witness unless the witness is available on Wednesday.

Defense attorney Don West said it didn't become aware of significance of the witness' testimony, if any, until after the trial began.

Nelson tabled the issue for the time being.

Earlier on Tuesday, the state issued a motion for inquiry into a photo showing West and his daughters eating ice cream cones with the caption, "We beat stupidity celebration cones" that was apparently posted on Instagram the same day Rachel Jeantel testified in court.

West called the state "irresponsible" for filing the motion.

The 29-year-old Zimmerman has pleaded not guilty to second-degree murder. He claims he acted in self-defense.

Jurors on Monday heard a series of recorded police interviews of detectives questioning Zimmerman about his confrontation with Martin in a gated community in Sanford.

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