One of the prosecution's most important witnesses in the Trayvon Martin murder case faces a second day of defense questioning about what she heard while on the phone with the teen right before he was killed.

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Nineteen-year-old Rachel Jeantel's testimony continued Thursday and is considered important to the state's case. She was the last person to talk to the 17-year-old Martin before his encounter with defendant George Zimmerman on Feb. 26, 2012, in Sanford.

Defense attorney Don West continued to cross-examine Jeantel Thursday morning asking about her phone interview deposition with Martin family attorney Benjamin Crump, challenging her about differences in her deposition.

West brought out a personal letter Jeantel wrote to Martin's mother, Sybrina Fulton. The state has no objection to the letter coming into evidence, but objected to Jeantel reading it. It was written in cursive by a friend based on what she said and signed the letter with a nickname, "Diamond Eugene." West read the letter aloud to jurors because Jeantel said she couldn't read cursive.

Jeantel said Crump asked her if the incident was a "racial thing" but claims his question is missing from transcript. Jeantel said she didn't know race was an issue in the Martin case three weeks after Zimmerman shot him. She said she feels now the shooting was a racial thing because Martin was being followed.

Jeantel said she didn't believe "creepy a** cracker" is a racial comment. She said she never told anyone about Martin's comment until a year after the shooting.

"It was a personal letter to his mother," Jeantel said when West asked why she didn't write anything about thinking it was racial in the letter.

West then implied that the Martin family hid Jeantel from police because Crump said the family didn't trust Sanford police. At a news conference in 2012, Crump said he was handing over information about Jeantel to the U.S. Justice Department.

Jeantel talked to ABC News using the alias "DeeDee" after Crump on March 19, 2012, before her interview with prosecutors on April 2. Jeantel said Fulton was sitting beside her along with Martin family attorney Natalie Jackson when the state attorney first questioned her. Jeantel said Crump was driving her to Fulton's house for the state attorney interview.

"I never thought I was a witness, a serious witness ...  an important witness," Jeantel said.

She told West she altered her story about Martin because his mom was in the room during the state attorney interview. Jeantel said she didn't want his mother to hear Martin use words such as "cracker." She also said she didn't originally tell Fulton she overheard Martin saying, "get off, get off."

"I did not think it was important," Jeantel said when West asked why she didn't tell Fulton.

West then focused on the timeline of the night with the 911 calls and Martin's phone call records. Jeantel said she told Martin to run and he did. Zimmerman said Martin was running at 7:11:41 and Jeantel said she told Martin to run until call disconnected at 7:11:47. The first 911 call was made at 7:16:11. Jeantel's testimony on Martin running appears to be consistent with Zimmerman's story and forensic times almost to the second, records show. What hasn't been stated is Zimmerman's location from 7:13:40 when Zimmerman's non-emergency call ends and 7:16:11, when the witness 911 call was made.

After nearly 90 minutes of cross-examination, Jeantel remained poised, composed and much less defensive than Wednesday's questioning, answering with "yes sir" and "no sir."

West even asked if Jeantel was OK because she seemed different from Wednesday's testimony, in his opinion. Jeantel said no one coached her about her performance on Wednesday and that she was acting differently on Thursday because she got sleep.

After a short recess, West showed Jeantel a map of the Sanford neighborhood, Retreat at Twin Lakes, before the state objected.

West then said, forcefully, "You don't know Trayvon Martin got hit. You don't know if Trayvon Martin didn't take his fist and drive it into George Zimmerman's face?"

Jeantel paused and said, "No sir."

West moved on to the the discrepancies in transcripts on whether she identified Martin as saying "get off." She first quoted "get off" in the April 2, 2012 inteview but couldn't then say for certain it was Martin saying it.

"Trust me, they messed up," Jeantel said, insisting the voice was Martin.

The jury was then brought out for the audio interview of Jeantel and prosecutor Bernie de la Rionda from April 2, 2012, to be played for the judge to decide if it will be admitted into evidence.

The defense says Jeantel says, "I couldn't hear it was Trayvon." Jeantel says she said "I could hear it was Trayvon."

The state objected for the defense bringing in that interview into evidence. The defense said it wants the jury to decide. The audiotape was played for the jury and Jeantel confirmed it was her saying "get off."

West then asked Jeantel to describe what "wet grass" sounds like, to which she responded, "wet." Jeantel said it sounded like someone rolling on Martin's phone headset. When asked to describe the rolling sound, she brushed the court microphone to simulate headset sound she heard and agreed with West that a sound like that could be caused by various things.