Amanda Knox thought she might rather die than spend another day in prison.
Sitting in her cold, grey prison cell, she even debated how she would end her life.
All she could see were the prison's 60 feet high walls, topped with barbed wire. Isolated and afraid, she watched other inmates through barred glass doors.
In her new memoir, "Waiting to Be Heard," to be released by Harper Collins on April 30, Knox details her four years in an Italian prison following the murder of her British roommate Meredith Kercher.
The book does not include her life after prison and her most recent nightmare, the ruling in March by Italy's Supreme Court that she must be tried yet again for Kercher's murder. The details of Knox's life since leaving her Italian prison cell and her shocked and angry reaction to the latest court ruling will be discussed in detail in her exclusive interview with ABC News anchor Diane Sawyer.
Knox, who has always maintained her innocence, was a target for inmates and the prosecution too, she writes.
In December 2009, after two years in prison, Knox was convicted of murder and sentenced to 26 years in prison.
Her boyfriend at the time of the murder, Raffaele Sollecito, was also convicted and sentenced to 25 years in prison. A third man, Rudy Guede, was also convicted and is currently serving a 16 year prison sentence.
Throughout her nearly 500 page autobiography, Knox insists she is innocent.
As legal setbacks piled up and the grind of prison life wore her down, Knox says it was only her family -- and their twice-a-week-one-hour visits and weekly phone calls home on Saturdays -- that kept her together.
It was during the year after Knox was convicted of murder, with the looming possibility of life in prison without parole that her suicidal thoughts kicked in.
She never shared these thoughts with a soul, not even her family, she admits.
Knox writes that she often wondered what would be her breaking point. She thought, if she lost her appeal, and her sentence was increased to life in prison, that would be more than she could bear.
At least with a 26 year sentence, she realized that she would be 46 years old upon release. At that age, she remembers thinking, there was still life left to live.
This story has been updated from an earlier version.