In the letter, sent to ABC7 news partner the Daily Herald, Peterson talks mostly about his children.
"All my children are exceptional kids just wanting a happy childhood after their little worlds were turned upside down almost three years ago. It's not bad enough their father is being held unlawfully after the state appealed a Will County judge's decision to not allow bad evidence at trial, but now my children's well being and security is now in jeopardy again," Peterson wrote.
To read the entire letter, click here.
Peterson also released the above picture of his children. He says he keeps it in his cell.
More information about Peterson's letter from jail can be found in Tuesday's edition of the Daily Herald.