The trial in Oslo has so far dealt with the rape that, according to the indictment, took place at an after-party at the Crown Prince and Crown Princess's estate, Skaugum, in 2018.
Høiby denies that he deleted anything on his phone to hide evidence and claims that he did it to protect the woman.
He also reacted strongly to his web searches being reviewed in the courtroom.
"I think it's ridiculous to bring that up. What the hell does that have to do with the case," he says, before starting to cry.
Searched for "rape"
Høiby, dressed in a blue wool sweater for the day, begins the third day of the trial by saying that he is "incredibly tired" and asks to be allowed to address the issue of his online search history himself.
According to Aftenposten, Høiby googled his own name along with the words "rape" and "sleep rape", several weeks before he was arrested for the first time.
During Thursday's questioning, the prosecutor focuses on various excerpts from the "bonus prince's" search history, including Google searches from 2015 when Høiby searched for "rape". The "bonus prince" explains this by saying that there were rumors that he had raped a woman, which he says is not true, and that he wanted to understand the different concepts that appeared on social media.
Video file among the evidence
He is also asked about various porn searches he has made, including those about sleeping women. Høiby explains that he does not remember exactly what he searched for.
As I said yesterday, I've searched for a lot of strange things.
Now retired police officer Stig Berg Larsen testifies about a video file found on Høiby's computer, where the plaintiff is seen lying on a sofa with her eyes closed. According to Berg Larsen, Høiby sent a text message to a friend saying that he had deleted everything on his phone before he was arrested.
Four videos featuring the woman have also been moved to a secret folder named "porrrr" in an app on Høiby's phone, according to Berg Larsen.
Denies rape
Also on Wednesday, Høiby cried in the witness box and said, among other things, that he had an "extreme need for affirmation" and a life characterized by a lot of partying, alcohol and drugs.
He denies rape and says that he and the woman had "awake and voluntary" sex. However, he says he does not remember much of the occasion nor that he recorded any films.
The woman who filed the complaint has testified about how everything went "black" during the after-party. According to the prosecution, she was knocked out during the suspected assault and believes she was drugged.
However, the information that women were drugged is not included in the indictment, and it is also denied by Høiby.
"Never drugged anyone as far as I know," he says.
Marius Borg Høiby is 29 years old and the son of Crown Princess Mette-Marit of Norway from a previous relationship with Morten Borg. Mette-Marit married Crown Prince Haakon in 2001.
Marius Borg Høiby is charged with 38 crimes, including assaulting a former girlfriend and four counts of rape. According to the prosecutor, they occurred while the victims were sleeping and were filmed by Høiby.
Høiby has previously admitted to certain crimes, but denied the rape allegations.
The trial is expected to last at least six weeks. Høiby faces up to 16 years in prison.
