Convicted sex offender Rick Thorburn, Tiahleigh’s foster father, is serving a life sentence for the murder of the 12-year-old on October 29, 2015.

He sobbed while reading a one-page statement – he says was written about four years ago – in the Coroner’s Court sitting in Brisbane on Tuesday.

But when questioned about the admission, further details and other allegations, Thorburn said he had no recollection.

“You can make up any story you like,” he told counsel assisting the coroner Kate McMahon while threatening to leave the proceedings.

“I don’t give a f***.”

Asked when he dug up the statement, Thorburn said it was about a month ago when told he was to attend the inquest.

He had a handwritten original of the typed version handed into the inquest, but said he threw it away on the morning of Tuesday’s proceedings.

Questioned why, he said: “This is the end of it. I don’t need it anymore.”

Thorburn said he had no recollection of being told by his wife on the day Tiahleigh died that his son had had sex with the 12-year-old.

Asked whether there may be a link between the circumstances of him killing Tiahleigh and finding out about the sexual relationship, he answered: “I don’t know.”

He also told the inquest he was “coerced into pleading guilty” earlier to multiple charges of sexual assault for offences unrelated to Tiahleigh.

Deputy State Coroner Jane Bentley excused Thorburn from the courtroom, but said he may be called back as she wanted to consider whether he was in contempt of court.

He told the inquest Tiahleigh walked down their driveway with a packed bag after the two had an argument.

He put his arm around her to walk her back to the house.

Reading from the statement he said he wrote when seeing a psychologist, Thorburn said he held Tiahleigh tighter when she struggled.

Thorburn said he told Tiahleigh to stop and put his hand over her mouth when she started screaming and swearing because it was late and there was a neighbour nearby.

He let her go when they got to the verandah and she fell to the ground.

Thorburn picked her up to put her on a seat, but she fell again and didn’t respond when he spoke to her.

“Her eyes were closed and I didn’t think she was breathing,” Thorburn said.

“I must have accidentally suffocated her with my hand over her mouth and holding her so tightly around her waist and stomach.

“I know that I am responsible for Tia’s death and it is something I struggle to live with

“I know sorry can’t take away the pain it has caused a lot of people, but I am truly sorry.”

Tiahleigh’s family hope to get some answers from the two-day inquest before Deputy State Coroner Jane Bentley.

Despite internal reviews and criminal trials, no one knows what happened to Tiahleigh in her final moments, a pre-inquest hearing was told last month.

“(Thorburn) has pleaded guilty to her murder but has never given an account, either on oath or otherwise, as to how he killed her,” McMahon said during the hearing.

Tiahleigh’s murder spawned two major reviews and resulted in stronger criminal checks for people seeking to become foster carers or wanting Blue Cards to authorise them to work with children.

In the hours before Tiahleigh died, she had been to a hip-hop dance class where she complained of stomach pains.

That same night, Thorburn’s son Trent confessed to his mother Julene that he’d had sex with the schoolgirl and feared the stomach pains were a sign she was pregnant.

Thornburn and his wife feared a pregnancy could mean Trent would go to jail, according to earlier proceedings.

That night, Julene, Trent and brother Joshua went out, leaving Tiahleigh home alone with Rick Thorburn for two hours.

She was never seen alive again.

Tiahleigh’s body – naked except for underpants – was badly decomposed when found by three fishermen on the banks of the Pimpama River on November 5, 2015.

Authorities haven’t been able to determine how she died.

Members of the Thorburn family were convicted of being part of the crime – Rick Thorburn for the murder, Trent for incest, and Julene and Joshua for being part of an elaborate cover-up.

Rick Thorburn was sentenced to 20 years in jail.

The family members are all expected to be called as witnesses during the inquest.