Anders Behring Breivik sought to convince an Oslo court on Wednesday that he is sane so that his anti-Islam ideology will be taken seriously and not considered the ravings of a lunatic, even though it would mean a prison sentence rather than psychiatric care.
The 33-year-old right-wing extremist has already said that being sentenced to closed psychiatric care would be "worse than death".
A first psychiatric evaluation last year concluded that he was suffering from paranoid schizophrenia, but a second opinion found him of sound mind.
On Wednesday, he challenged the first examination, which he claims contains "more than 200 lies" in a diagnosis he has called "the ultimate humiliation."
"These are ill-willed fabrications," Breivik told the court Wednesday, referring to passages from the report.
He later added: "They may not be ill-willed, but they are in any case wrong."
Psychiatrists Synne Soerheim and Torgeir Husby were appointed by the Oslo district court to carry out the first evaluation.
Their conclusion in November that Breivik was psychotic cleared the way for him to be sent to a closed psychiatric ward for treatment instead of prison.
But the diagnosis caused uproar in Norway, where many were astounded that the man who methodically planned his attacks for years and then executed them with precision could be found not responsible for his actions.
The court therefore ordered a second opinion by two other experts, who concluded earlier this month that Breivik was sane.
A third panel of experts charged with verifying the validity of the reports has found weaknesses in the second evaluation and asked the authors to provide additional information.
It will ultimately be up to the judges to determine whether he is sane when they hand down their verdict in July.
Breivik told the court Wednesday that "80 percent of the content from the interviews (on which the first two psychiatrists based their conclusions) is invented."
The two experts drew their conclusion "very early" and aimed the rest of their work at proving their diagnosis was correct, he said.
"They were emotionally affected (by the attacks) and they were not competent to evaluate a person responsible for political violence," he said.
"If I had read a description of the person they describe, I would have agreed: this person needs psychiatric care," he said, adding: "But the person described in this report is not me."
Breivik reiterated Wednesday that he does not want to "end up in an asylum" and said he had exchanged letters with a Swedish militant nationalist who described his own treatment in a psychiatric ward as "a chemical lobotomy."
"He says it's awful. He sits at a table drooling," he said.
Breivik has been charged with "acts of terror" and faces either 21 years in prison -- a sentence that could be extended indefinitely if he is still considered a threat to society -- or closed psychiatric care, possibly for life.
Earlier this week, he lamented in court that his sanity was being questioned.
He claimed to be the victim of "clear racism" and accused the prosecution of trying to "delegitimise" his Islamophobic ideology.
"If I had been a bearded Jihadi there would be no report at all... There would not be a need for a psychiatric evaluation," he said.
Breivik set off a bomb near the government offices on July 22 that killed eight people, then went to nearby Utoeya island where he killed 69 people, mostly teens, attending a Labour Party youth camp.
He has said his attacks were "cruel but necessary" to stop the ruling Labour Party's "multicultural experiment" and the "Muslim invasion" of Norway and Europe.