(NBC NEWS) -- Defense attorney Don West continued an aggressive cross-examination of the state's key witness in the George Zimmerman murder trial Thursday.
Rachael Jeantel was on the phone with Trayvon Martin just minutes before he was killed and testified she heard the sounds of his confrontation with Zimmerman.
"She may be the most important part of the case," says legal analyst Kendall Coffey. "It's going to be difficult for the prosecution to get a conviction if they jury decides Rachel Jeantel is not worthy to be believed."
The defense repeatedly tried to point out inconsistencies in her testimony and questioned not only what she told the jury she heard, but also how she reacted when that phone call was disconnected.