An expert sociologist says the testimony of far-right mass killer Anders Breivik should not be curtailed because his “repellent” views and rambling speech will actually put people off extremism.

Professor Thomas Hylland Eriksen, who has been called as an expert witness in Breivik’s trial, said self-confessed killer’s beliefs about immigration were “widely shared” in an interview with British broadcaster ITN. 

In a scene unimaginable in many countries, Breivik this week got the chance to explain his fanatical views to the court and the world, unrepentant and dressed in a business suit. Prosecutors and lawyers for the families of his 77 victims even shook his hand.

The 33-year-old far-right militant gave a rambling hour-long address to the court on Tuesday, reading from a statement that essentially summarized the 1,500-page anti-Islamic manifesto he posted online before his bomb-and-shooting rampage nine months ago.

"The attacks on July 22 were a preventive strike. I acted in self-defense on behalf of my people, my city, my country," Breivik declared, demanding to be found innocent of terror and murder charges. "I would have done it again."

Breivik: I was motivated by goodness and 'would have done it again'

Breivik has five days to explain why he detonated a bomb outside government headquarters in Oslo, killing eight people, then drove to a nearby resort island, where he massacred 69 others, mostly teens, at a summer youth camp run by the governing Labor Party.

Breivik, who has admitted carrying out the grisly acts, boasted they were the most "spectacular" by a nationalist militant since World War II.

Breivik’s speech, which angered victims’ family members who were present, was not broadcast on television because of a court order preventing live feeds during the killer's testimony.

However, Professor Eriksen told ITN Breivik's speech was more likely to harm his cause.

Eriksen said:

"Parts of his world view are clearly widely shared, not by a majority but by substantial groups who feel globalization is not going their way, that their country is being invaded by a foreign alien enemy Muslims and feel that they are being ruled by spineless multiculturalists who don't see the dangers of Islam.

"I've been of two minds myself but I've reached a conclusion that it's a good thing to give him this platform because he doesn't appear credible, he's not very charismatic - he does't have ... the appeal that would attract people so I think he works more like a repellent, a mosquito repellent against right-wing extremism because people who see him realize how bad it would get if they are attracted to these crazy notions of purity of race."

On Monday, Norwegian prosecutors and even lawyers representing the families of victims shook Breivik's hand as the trial opened, raising some eyebrows. Prosecutors shaking hands with defendants would be a rare sight in the U.S., as well as in neighboring Sweden and other Nordic nations.

"That was a bit strange," said John Christian Elden, who represents some survivors but is not participating in the trial.

Breivik had asked to wear a uniform in court in pretrial hearings but was rebuffed, and he appeared at the trial in a business suit and tie, his thinning hair neatly combed.

"We don't have orange jumpsuits and that kind of thing in Norway," his lawyer Geir Lippestad said. "This is a completely normal way to dress in a Norwegian court, even in a serious criminal matter."

'Childishly defiant'
On Wednesday Breivik  told the court he had been inspired by Serbian nationalism.

Anders Breivik to Norway court: I killed 77 people but am not guilty

Asked how he had changed from a teenage vandal on Oslo's prosperous west side to a methodical killer, he said he helped found a militant group called the "Knights Templar" in 2001 but refused to give any details to back up the claim. 

The original Knights Templar were a medieval brotherhood of European knights that pursued anti-Islamic crusades. 

Breivik deflected five straight questions about supposed allies and repeatedly tried to tell prosecutors how to phrase themselves. He became visibly irritated and swiveled a pen in his hand. 

Breivik's trial, to last 10 weeks, turns on the question of his sanity and thus whether he can be jailed. He has said that an insanity ruling would be "worse than death." 

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He came off as "childishly defiant," Tore Sinding Bekkedal, a survivor of the island massacre, said during a break on Wednesday. "He's trying to steer the proceedings and failing." 

If found mentally sane — the key issue to be decided in the trial — Breivik could face a maximum 21-year prison sentence or an alternate custody arrangement that would keep him locked up as long as he is considered a menace to society.

If declared insane he would be committed to psychiatric care for as long as he's considered ill.

The Associated Press contributed to this report.

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A nun and a priest stand outside the Monastery of the Cross after it was defaced with graffiti on Tuesday. The monastery, built on the spot where tradition holds the tree from which Jesus' cross was made, was defaced with graffiti bearing the hallmarks of militant Jewish settlers, police said.

JERUSALEM -- A Jerusalem monastery, built on the spot where tradition holds the tree from which Jesus' cross was made, was defaced with graffiti bearing the hallmarks of militant Jewish settlers, police said on Tuesday.

"Death to Christians" was daubed in Hebrew on the outer walls of the Monastery of the Cross, an 11th-century fortress-like holy site situated in a valley overlooked by Israel's parliament.

Army Radio reported that "Maccabees of Migron" was painted on the monastery, too, The Associated Press reported. Maccabees were ancient Jewish heroes, and Migron is an unauthorized settlement facing a court-ordered evacuation. 

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Such acts originally targeted West Bank mosques but have recently expanded to include a mosque inside Israel, Israeli military bases, and now, a Christian holy site.

Police spokesman Micky Rosenfeld said the words "Price Tag" were also painted overnight by the vandals, who damaged two cars parked outside the monastery in the attack, according to Reuters.

The slogan, used by Jewish settlers in vandalism attacks on mosques and Palestinian homes in the occupied West Bank, refers to the retribution they say they will exact for any attempt by the Israeli government to curb settlement in the territory.

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"I am a priest and I forgive," Father Claudio of the monastery, which is administered by the Greek Orthodox church, told Reuters.

Rosenfeld said police had opened an investigation.

Reuters and The Associated Press contributed to this report.

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(This report has been updated to correct an error.)

By Andy Eckardt, NBC News

BERLIN – Irmela Mensah-Schramm has embarked on her very personal "combat mission" almost daily for 26 years. Her weapons? A scraper, nail-polish remover, a camera and lots of courage.

Come rain, heatwaves or stormy weather, the 66-year-old sets out to battle what she calls "extremely disturbing" neo-Nazi and racist graffiti, stickers and posters that blight the streets of Germany's capital.

The retired special-needs teacher has now removed more than 90,000 stickers and scribblings.

"Even when I injured my leg several years ago and was walking on crutches, it did not stop me from removing the muck off traffic light poles, bus stops or building walls," Mensah-Schramm says.

Mensah-Schramm travels by commuter train to areas she believes are right-wing strongholds, places where xenophobic propaganda and spray-painted Nazi symbols mix with gang-related graffiti and the more colorful works of spray-paint artists.

'Appalled'
Her "vocation" started with a single neo-Nazi sticker on a street light outside of her apartment in the upmarket Berlin-Wannsee area.

"One morning, I saw a banned Nazi symbol well visible on a lamp post and was appalled that people in my neighborhood ignored it day in and day out, without removing this trash," Mensah-Schramm recalls.

"Only a short while later, I witnessed an incident in which my Indian brother-in-law became the victim of racist bashing. This shocked me so much that I decided to act."

John Macdougall / AFP - Getty Images file

Anti-Nazi activist Irmela Mensah-Schramm scrapes a sticker off a drainpipe in eastern Berlin's Lichtenberg district on December 20.

She documents much of the offensive material in photographs and has compiled a scrapbook, which she always carries with her. Mensah-Schramm calls her project "Hate Destroys".

"For many years, I have been displaying my pictures in exhibits across the country," Mensah-Schramm says. "I talk about my experiences in schools and I regularly host workshops with children and students, generating awareness for the bad impact of these ugly racist messages."

Swastikas
Even ill health hasn't stopped her determined drive to wipe out extremist propaganda. After undergoing a cancer operation at a Berlin hospital in 1995, Mensah-Schramm found two swastikas painted in a stairwell. She rushed back to the nurses, asked for acetone and scrubbed away as much as she could before becoming too weak to finish the job. It was the first day Mensah-Schramm was able to get out of bed.

"In some journeys, I need to take tougher measures with black spray-paint or anti-graffiti solvent to remove writings off walls, and sometimes I even ask people on the street to help me out, if I cannot reach the graffiti," Mensah-Schramm says as she walks past run-down apartment buildings in an economically depressed neighborhood in the Berlin suburb of Koenigs Wusterhausen, which was once part of communist East Germany.

"Look, that is my work," she proudly points out, as she walks past a black square, which was once a swastika that she recently painted over.

Her message is clear: Don't look away.

"You cannot achieve something by doing nothing," explains Mensah-Schramm, whose husband was born in Ghana.

"This type of xenophobic propaganda on the streets can help to spread dangerous ideologies, which can be part of a radicalization process that ultimately can lead to extreme violence," she says, referring to recent revelations about a neo-Nazi terror cell that shocked Germany and led to a nationwide debate about the danger of right-wing extremism in the country.

Murder spree
Two men, Uwe Mundlos and Uwe Boehnhardt, and their 36-year old female accomplice, Beate Zschaepe, formed the so-called National Socialist Underground (NSU). The group is believed to be responsible for the murders of at least nine small businessmen of Turkish and Greek origin between 2000 and 2006, as well as the slaying of a police officer in 2007.

Much to the embarrassment of German authorities, the country's law enforcement agencies only connected the crimes and their xenophobic motives in late 2011 after two of the three cell members committed suicide, following a bank robbery that put police on their trail.

German investigators originally suspected that the victims were most likely killed by fellow immigrants and might have been involved in gang-related crimes.

While critics say that German authorities had turned "blind on the right eye", by focusing instead on tackling Islamist terrorism, lawmakers set up an anti-terror center for right-wing extremism in December. Last month, Germany's parliament also appointed a commission of inquiry into the series of killings.

The German government has also established a database aimed at better coordination in the fight against violent neo-Nazis, partly because the NSU terror cell apparently remained in the shadows for so long due to poor lines of communication between different national security agencies and state authorities.

"Attacks on local politicians and violent acts against foreigners show that the goal is to spread fear and terror," Heinz Fromm, the head of Germany’s domestic intelligence agency, told a recent symposium in Berlin.

'Brutality'
Germany's domestic intelligence agency estimates that there are about 9,500 potentially violent neo-Nazis among the 26,000 right-wing extremists in the country.

"For years, we have been seeing that brutality within right-wing extremism has been on the rise," says Dr. Alexander Eisvogel, vice-president of Germany’s domestic intelligence agency.

• Homes raided after neo-Nazi torchlight parade

However, Mensah-Schramm insists that she remains unafraid.

"I have been threatened many times by neo-Nazis, who have seen me remove their works,” she says. “And once, I came across big letters written on a wall that read: 'Schramm, we will get you'.

"Another time, I found my photo illegally posted on a well-known neo-Nazi website, where the subtitle indicated that nobody would care if I was dead," Mensah-Schramm describes.

She filed an official complaint over the violation of her personal rights. "Unfortunately, that got me nowhere because the server for the page was based in the United States," Mensah-Schramm says.

Andy Eckardt, NBC News

This neo-Nazi sticker that reads "nationalism" in German is among the thousands that have been removed by Irmela Mensah-Schramm.

In fact, German authorities are facing a growing challenge when it comes to online enforcement.

Extremist groups are turning to web servers in the United States to host their content and spread their messages beyond the jurisdiction of local authorities. While displaying of Nazi symbols and the incitement of racial hatred are outlawed in Germany, neo-Nazi websites take advantage of free speech laws in the United States.

As the retiree counts sticker number 70,076, removed at a bus stop outside a local high school, she turns and says, "There are these small, but very rewarding moments."

"A former neo-Nazi, who had massively threatened me in the past and later exited the scene, stopped me on the street one day," Mensah-Schramm says with a choked voice. "He took off his sunglasses, looked me straight in the eyes and said that he wanted to thank me for never giving up my fight.

"I was so overwhelmed by the gesture that I started to cry," Mensah-Schramm says, before walking off to complete her mission of the day.