After Mr Hastie died in April 2019, audio of 13 "interrogations" found on Beutel's phone indicated he was struck almost 250 times.
Suffering a psychotic illness exacerbated by substance abuse, Beutel can be heard making delusional claims amid Mr Hastie's screams, Brisbane Supreme Court heard.
She not only believed Mr Hastie was involved in a pedophile ring but also a DNA experiment, accusing him of stealing 16 fetuses from her to create a "superior race".
Beutel - now 43 - also claimed Mr Hastie had injected her with the SARS virus as well as mercury.
The court heard witnesses had seen Beutel behaving erratically, repeatedly punching Mr Hastie and accusing him of being a pedophile up to six days before his death at Maleny, north of Brisbane.
One witness said Beutel described Mr Hastie as "putrid scum" and that she was going to take him out to a forest to kill him.
She told another that Mr Hastie had "stolen her eggs and DNA".
Others noticed Mr Hastie with facial bruises and looking "defeated and severely beaten".
Days later another witness went to Mr Hastie's house after hearing yelling and was initially stopped by Beutel from entering before seeing the 63-year-old inside with two black eyes and a bleeding arm.
Police were called but when they arrived at Mr Hastie's house, no one was home.
Later that morning Beutel visited a neighbour and asked them to call the police because Mr Hastie had fallen down the stairs.
Mr Hastie was pronounced dead at Maleny hospital a short time later.
His injuries were consistent with being struck with a broom stick or a metal rod and he died from complications from multiple blunt force injuries, his autopsy said.
Beutel repeated her "bizarre" claims about Mr Hastie when interviewed by police.
She also told officers she was related to the Queen and that she could "get justice through her connections".
Police then found her phone audio recorded over two days that included 248 "striking sounds" and Mr Hastie groaning, screaming in pain and begging not to be hit any more.
One of the recordings - lasting 13 minutes - was set to be played on Wednesday but Justice Paul Freeburn opted to listen to it outside court.
Beutel was suffering from a serious mental illness that caused a psychosis made worse by alcohol and drug consumption at the time, the court heard.
"The tragic death of Colin Hastie was caused by a woman who was completely detached from reality," defence barrister Catherine Morgan said.
She said psychiatric reports indicated at the time Beutel was "floridly psychotic", driven by the intensity of her delusions.
"She was a very unwell woman," Ms Morgan said.
The fact that Beutel was recording her repeated assaults of Mr Hastie indicated the "depth of her psychosis", she said.
Ms Morgan said Beutel's psychosis was now in remission and that she had gained insight with improved mental health, acknowledging that her "bizarre ideas" were now false.
Beutel pleaded guilty to manslaughter and will be sentenced on Thursday.
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