The trial of two boys accused of Ana's murder also heard that before her death, she had engaged in “attention seeking” and had set up fake accounts to “bully herself.”
The youths, aged 13 at the time, have pleaded not guilty to the murder of Ana (14) at Glenwood House, Laraghcon, Clonee Road in Lucan on May 14 last year.
Her naked body was found at the disused farmhouse three days after she was reported missing.
One of the boys, Boy A, has also denied a charge of aggravated sexual assault.
It is the prosecution's case that Boy B "lured" Ana to the derelict farmhouse and then watched "voyeuristically" as the other boy sexually assaulted and murdered her.
Patric Kreigel told the court he was from Paris and had been a lecturer in French at DIT before retiring and becoming a homemaker.
He recalled adopting Ana when she was two and a half years old and that her national school years were happy ones.
“She was a happy child,” he said. “She was excited about going to secondary school.”
Ana had started walking to school herself and was looking forward to being more of an adult and less of a child, he said.
Her excitement about secondary school changed and she got “stressed” which was not like her at all, he said.
“The stories she had were not very happy stories,” Mr Kriegel said.
This related to her being bullied. He agreed with Brendan Grehan SC, prosecuting, that Ana was probably “a little bit different herself.”
His daughter was unique and “full of fun,” he said.
“I think people did misunderstand her,” he said.
She could not hate anyone even though some of the people concerned were bullying her.
She was quite often disappointed, she would try to make friends but she was impulsive and would say the wrong thing.
“She was a teenager,” Mr Kriegel said.
The court heard Ana had been friends with a boy who started to say he was suicidal and he “didn’t exert a very good influence on her.”
Ana had told her father she felt invisible and “began to engage in attention seeking antics,” Mr Grehan said.
Mr Kriegel agreed that Ana, who was “quite good at IT” had “set up some online accounts, fake accounts bullying herself.”
The school discovered the accounts were fake and she eventually owned up.
Ana’s phone activity was supervised and she knew that if she did not let her mother do this, there would be “no more phone.”
She would go out walking with her headphones on listening to music and initially her parents would know where she was through the Find My iPhone app.
However, she left the Family Sharing on the app “and then I couldn’t see where she was,” Mr Kriegel said.
There was a strict rule that she could not stay out after dark.
Mr Kriegel said Ana was extremely happy in the house and “told us she would never leave the house.”
She had not managed to make any friends of her own and that was a “source of some unhappiness for her.”
On the day she disappeared, she had been to a counselling session and changed into very distinctive clothes.
Mr Kriegel was in the back garden and heard the front doorbell ring at around 4.55pm.
He went into the hall and Ana was whispering at the front door, but “that was not unusual because a lot of teenagers seem to whisper.”
This did not last long and she went back upstairs and came down wearing a distinctive black hoodie top with white writing.
“I said Ana, you know you are supposed to study because she had exams the following week,” Mr Kriegel said. “She said ‘what? Nobody told me that,’ and I said OK but don’t be long and she answered me back, ‘no, I won’t be long’. I believe that she meant it. I knew from the way she was saying it.”
Mr Grehan asked what kind of expression was on her face.
“She gave me a big smile when she left, she was happy,” he said.
He did not know where she was going or who she was talking to, but learned the boy’s name.
He had forgotten to ask where she was going and went to the front room to look out and saw she was going in the direction of the park.
She was walking with the boy who was smaller than her, to her left. He was wearing a small backpack on his back.
Mr Kriegel was “not particularly alarmed” at how she had left as she was smiling.
His wife Geraldine arrived at around 5.20pm and he told her he had left with Boy B. She replied “what the hell was she doing with him? No-one calls for Ana.”
He then recalled the subsequent search, and identifying Ana’s body after it was discovered.
He was shown pictures of what she was wearing, and her phone. He was “100pc” sure the black hoodie top was hers.
Earlier, Mrs Kriegel told prosecution counsel Brendan Grehan SC that she returned home from work about 5.20pm on May 14. She had earlier missed a phone call from Ana at 4.02pm and again at 4.03pm but she was in a meeting and couldn't answer.
Mrs Kriegel said she rang Ana around 5.10pm, when she was on the train home from work, but Ana hadn't answered.
Mrs Kriegel said her husband Patrick was in the garden when she got home.
"Where's Ana?", she asked.
Patrick told her that Ana had left the house with Boy B.
"What was he doing with Ana?" she asked her husband. "He has nothing to do with her," she told the Central Criminal Court.
Mrs Kriegel said that "nobody called for Ana" because she had "no friends".
She said she immediately text Ana "home now".
Again there was no answer, so Mrs Kriegel said she text Ana "answer me now or I'm calling the police".
Mrs Kriegel said she was torn between feeling like a paranoid and an over protective mother.
She then asked her husband what direction Ana had gone when she left home, and she went searching the area.
She couldn't find Ana, so she returned home around 6pm and had her dinner.
She then got her car, and went out searching for Ana a second time. She thought Ana might still be with Boy B, but she said that she "couldn't see her anywhere".
Mrs Kriegel said she later contacted a friend, a retired detective, and he told her to go to the gardai, and around 9pm she went to Leixlip Garda Station.
Mrs Kriegel said it was unusual for Ana not to answer her phone, and even if Ana was annoyed with her mother, she'd respond to a text, saying "I'm not answering you".
She said she spent the next three days searching for Ana, and she later identified her daughter's body in the Dublin City Morgue.
Earlier, Mrs Kriegel told the court that the family had a party on the day before Ana went missing. They'd had pizza, and Ana had gone to the chipper to get a spice bag because she didn't like pizza.
Ana had later gone upstairs and created a long video for YouTube, she said.
On May 14, Mrs Kriegel said she went upstairs to wake Ana before she went to work. She kissed her goodbye, and Ana asked her to write a note for school to allow Ana to attend her counsellor later that day.
Mrs Kriegel agreed with Damien Colgan SC, for Boy B, in cross examination, that she found a condom under Ana's pillow a week before her disappearance.
She said that when she was questioned by gardai after the disappearance her mind was "frantic".
Cross examined by Patrick Gageby SC, for Boy A, she said Ana could get angry and throw things around the room, but she "wouldn't hurt a fly".
She agreed it had been suggested that they would get a punch bag as a vehicle to absorb that energy.
The trial continues before Mr Justice Paul McDermott and a jury of eight men and four women.