For the first time, we are hearing from the teenager believed to be the last person to talk to Trayvon Martin moments before his deadly confrontation with George Zimmerman.

The teen, known only as "Witness 8," is considered to be the prosecution's key witness, but Zimmerman's attorneys said she lied during a deposition by the Martin family's attorney, Benjamin Crump.

A new motion filed Monday said the state knew Witness 8, said to be a girlfriend of Trayvon Martin's from Miami, had been lying, but never came out with it.

The defense listed two main issues in its motion:

1. Witness 8 said she missed Trayvon Martin's funeral, because she was in the hospital.

2. The state had said the witness was a juvenile, but then later learned she was actually 18 years old. She is currently 19.

Zimmerman's attorneys have criticized Crump's interview with Witness 8, saying it was hardly audible and appeared to be chopped up in parts.

The following is part of the phone interview, conducted days after Trayvon Martin died in February 2012:

Benjamin Crump: "Attorney Crump and the family here."

"We saw from the phone records you and Trayvon talked pretty much all day. Can you just walk me through the day -- how many times you talked to Trayvon that day, and what kind of state of mind he was in?"

Witness 8: "Uh, we talked all day. From 9 o'clock, texting and stuff. No, around 10. He was good."

Zimmerman's attorneys said they want the state prosecutors to be punished for being "unethical," saying they hid lies about Witness 8 for months.

The motion also says Witness 8 was sitting with Trayvon Martin's family during the interview, something the defense says means the entire statement could be an issue.