A suspected gunman accused of an attempted terrorist attack on an Oslo mosque and separately killing his teenage stepsister appeared in court Monday for a hearing, but his defense lawyer said he "will use his right not to explain himself for now".
Unni Fries, the suspect's lawyer, declined to offer any further information and told AFP that she needed "much more time to get into the case".
Authorities say that the suspect holds "far-right" and "anti-immigrant" views.
A 65-year-old man is being hailed a hero for holding down a gunman who tried to open fire in a mosque in Norway until police arrived.
Hours after the attack, the body of a young woman was found in a home in Baerum and police on Sunday confirmed it was the suspect's 17-year-old stepsister.
The 21-year-old was arrested on Saturday after he entered the Al-Noor Islamic Center in Baerum, an Oslo suburb.
"We're investigating this as an attempt at carrying out an act of terrorism", Assistant Chief of Police Rune Skjold told a news conference on Sunday.
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The Norwegian police security service, PST, which monitors and investigates extremist threats, said on Monday it had received a tip regarding Manshaus previous year, but had not launched an investigation at the time.
Dagbladet, one of Norway largest newspapers, reported that on day of the attack, Manshaus wrote online he had been "chosen" by "Saint (Brenton) Tarrant", the Christchurch gunman.
The name of the Oslo mosque is similar to the one in the New Zealand attacks.
The post ended with the words "Valhalla awaits", a mythological Norse reference to the afterlife for those who have died in battle.
The Oslo attack took place on the eve of the Islamic celebration of Eid Al Adha, marking the end of the Hajj pilgrimage, stoking fears among Norway's Muslims.
In 2011, anti-Muslim neo-Nazi Anders Behring Breivik massacred 77 people in Norway's worst peacetime atrocity, the majority of them teenagers at a youth camp.
In Norwegian media, neighbours and acquaintances have meanwhile described the suspect as a happy and well-adjusted person, but whose behaviour had changed during the past year. "I think it's a word-wide challenge in a sense", Norwegian Prime Minister Erna Solberg said on August 11, referring to hate speech.