Hernandez's sexuality had also played a role in the murder for which the disgraced Patriot tight end was serving life without parole in the Souza Baranowski Correctional Center, the report said.
Hernandez may have fatally shot his old pal, Odin Lloyd, in 2013 because Lloyd had been taunting him about his bisexuality, the report said.
At the time, Hernandez had been carrying on a longtime affair with a male former high school classmate, a man who was forced to testify in front of a grand jury in the Lloyd murder, the report said.
Lloyd and Hernandez were dating sisters at the time. Had Lloyd spilled the beans to his girlfriend, Hernandez's fiance, Shayanna Jenkins, might have found out about the Patriots star's sexuality, the magazine reported.
The letters to his fiancee and daughter were found next to a Bible opened to John 3:16, the same verse that Hernandez had scrawled on his forehead in marker.
That verse reads: "For God so loved the world that he gave his one and only son, that whoever believes in him shall not perish but have eternal life."
Hernandez, 27, reportedly planned his suicide for weeks and had given away most of his belongings to fellow inmates.
Massachusetts District Attorney Joseph D. Early Jr. said Thursday that "an investigation into the death by the State Police Detectives assigned to the District Attorney's Office and Department of Correction investigators found cardboard jammed into the door tracks of his single-inmate cell to impede entry into the cell".
"There were no signs of a struggle, and investigators determined that Mr. Hernandez was alone at the time ..." he wrote.
"Mr. Hernandez was locked in his cell about 8pm and no one entered the cell until a correction officer observed him at 3.03am and forced his way through the impeded door to render aid."
His brain was released to Boston University after the family wanted it studied for possible concussion-related damage.
Hernandez was serving a life sentence for the 2013 murder of Odin Lloyd, a semi-professional football player who was dating the sister of Hernandez's fiancee.
He killed himself five days after being acquitted in a 2012 double slaying that prosecutors said was fuelled by an argument over a spilled drink.
Prison officials told WBZ Boston that "Hernandez hanged himself utilising a bed sheet that he attached to his cell window" in the Souza Baranowski Correctional Center.
He may also have smoked some synthetic marijuana, known as K2, in his cell the night before, the outlet reported.
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Samaritans 0800 726 666
If it is an emergency and you feel like you or someone else is at risk, call 111.
