She added he got what he deserved when he died in a shoot-out in the Idaho wilderness.
In an unusual move, Hannah Anderson went online following her rescue on Saturday and started fielding hundreds of questions through ask.fm, the social-networking site.
The postings started on Monday night, hours after her father requested the family be allowed to grieve and heal in private.
Police have said little about their investigation. Jan Caldwell, a spokeswoman for the San Diego County Sheriff’s Department, said authorities were aware of the online comments, but could not confirm that the account was Hannah’s.
However, during the lengthy series of posts, a questioner asked Hannah to post a photo, and she complied. The image showed her with a wide smile.
Dawn MacNabb, whose son, Alan, is one of Hannah’s closest friends, confirmed the postings were by the teenager. He spoke on the phone with Hannah on Tuesday and urged her to delete some of the postings.
Hannah was kidnapped on 4 August by James Lee DiMaggio, 40, her father’s best friend, who was like an uncle to her and her eight-year-old brother, Ethan.
DiMaggio had invited the children and their mother, Christina Anderson, 44, to his house in Boulevard, a rural town 65 miles east of San Diego.
“He told us he was losing his house because of money issues, so we went up there one last time to support him, and to have fun riding go-karts up there, but he tricked us,” Hannah wrote.
She said DiMaggio tied up her mother and brother in his garage. Their bodies were found after a fire destroyed the home.
“I wish I could go back in time and risk my life to try and save theirs. I will never forgive myself for not trying harder to save them,” she wrote.
Hannah said she “basically” stayed awake for six days and DiMaggio ignored her requests for food. She couldn’t try to escape because DiMaggio had a gun and “threatened to kill me and anyone who tried to help”.
She was too frightened to ask for help when four horse riders met the pair in the wilderness on Wednesday 7 August.
“I had to act calm as I didn’t want them to get hurt. I was scared that he would kill them,” Hannah wrote.
The girl said DiMaggio threatened to kill her if she didn’t help hide his blue Nissan Versa with branches. Authorities discovered the car on Friday, leading to her rescue the following day.
Asked if she would have preferred to see DiMaggio get a prison sentence, instead of being killed by FBI agents, she said: “He deserved what he got.”
Hannah acknowledged being uncomfortable around DiMaggio even before the ordeal, saying he had once told her that he was drawn to her.
She didn’t tell her parents because DiMaggio was her father’s best friend “and I didn’t want to ruin anything between them”.
When one commenter said Hannah’s responses lacked emotion, she wrote: “I’m trying to stay strong. You don’t know I could be crying answering these questions at the moment.”