Ferry added, "I am a drug addict. That's my crime."
Police arrested Ferry in March after 15-year-old Anne Kasprzak was found dead in the Jordan River. According to a probable cause statement filed at the time with the Salt Lake County Jail, Draper police interviewed a witness who allegedly saw Ferry assault Kasprzak at a south valley home after she refused to have sex with him.
Another probable cause statement said that 30-year-old Veanuia Vehekite assisted in removing an unconscious Kasprzak from Ferry's home. The witness said Kasprzak was alive but unconscious when she was carried away in a tarp from the home by Vehekite and another man, who is not named in the statement.
Police say Ferry, Vehekite and the other man left the home and returned with their clothing "all bloodied a few hours later."
Charges, however, have not been filed against either men relating to the girl's death.
Instead, Ferry remains behind bars on unrelated charges of aggravated kidnapping and witness tampering for allegedly forcing a woman to stand in front of a dart board while someone threw darts at her as "revenge" for money he said she owed him.
On Friday, a preliminary hearing in that case was set for later this month.
Vehekite, meanwhile, is also being held on charges in another case.
Officials from Draper police and the Salt Lake County Attorney's Office did not immediately return calls seeking comment on the murder investigation.
In a statement issued last month in response to Ferry's letter and proclamation of innocence, James and Veronica Bratcher, the slain girl's parents, said the loss of their daughter has caused more frustration than a delay in prosecution.
"While we wonder every day why she was killed, we suspect there will never be a good enough answer to console the many lives that must go on without her that have been forever changed by our loss," they wrote.