Read Sheila Trott's letter about Kelly Brennan's murder

While behind bars awaiting trial in 2010 for the murder of Kelly Brennan, Sheila Trott wrote a 22-page account of what she saw the night Brennan was brutally murdered.

In her chronology, the now-convicted murderer says she witnessed her friend being beaten and taken to an isolated beach area. Is she telling the truth or is this a confession letter?

"It's not a confession letter. That's my account of what happened that evening," Trott told "48 Hours" correspondent Peter Van Sant.

Watch as Van Sant questions Trott about the letter -- and how he helped search for the document.

Click through to read excerpts of the letter Trott wrote to a friend.