Published: Nov 02, 2010 8:54 PM EDT
Updated: Nov 02, 2010 5:54 PM EDT

ORLANDO, Fla. (AP) - Casey Anthony's mother wrote in a letter last summer that she has never given up believing that her daughter is innocent of murdering her infant granddaughter.

The letter Cindy Anthony wrote to her daughter, Casey, in jail last summer was among 1,000 pages of documents released Tuesday by the State Attorney's Office. Cindy Anthony says in the letter that after Casey Anthony's trial is over they will look for 2-year-old Caylee Anthony together.

Casey Anthony has pleaded not guilty to killing her daughter and says a baby sitter kidnapped Caylee.

The documents also show that detectives investigating Caylee's disappearance sought and received court permission to trace the phone calls of Casey Anthony, her parents and brother, and as well as put tracking devices on their cars.