Sonja Renee Callahan was in federal custody in Odessa when she wrote the letter to her sister several months ago.
Now, Callahan is being held in a federal prison in North Texas, and investigators are allowing the letter to be released.
Reporter Victor Sotelo of KTAB-TV in Abilene recently spoke with Callahan by phone about the letter.
Parts of Callahan's interview had to be bleeped out to protect the investigation, and not all of Callahan's phone interview from prison can be released.
However, excerpts from that phone interview are available, by clicking on the video.