Friday's twin attacks in Norway that killed 76 people have sparked growing outcry at the country's penal code, under which even the man now accused in the mass killings would face a maximum penalty of only 21 years in prison if convicted.

If found guilty in the massacre and given that maximum sentence, Anders Behrin Breivik, 32, would serve roughly 100 days in prison per killing.

"So many innocent people have been killed that I think he doesn't have the right to live," Mari Kaugerud wrote on her Facebook group "Yes to the death penalty for Anders Behring Breivik," which already has 1,783 members, the AFP reports.

Dozens of similar groups have sprung up since Friday's killings, some calling for the death penalty, others for life in prison.

"People like that shouldn't be able to get out among normal people," a 31-year-old Iranian-born shopkeeper identified only as Mustafa told AFP. "If he gets 21 years, how old will he be? 53! No, he's ruined too much to ever get out."

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Breivik is accused of the initial bombing in the capital of Oslo, as well as the subsequent shooting rampage at a Labor Party youth camp on an island outside the city. He is said to be an anti-Muslim extremist who left a online manifesto before carrying out the attacks.

The court ordered him held for eight weeks while prosecutors investigate, four of which will be in isolation, saying Breivik could tamper with evidence if released. Typically, the accused is brought to court every four weeks while prosecutors prepare their case, so a judge can approve his continued detention. Longer periods are not unusual in serious cases.

Breivik has confessed to both assaults but denied criminal responsibility for them and pleaded not guilty Monday. He told authorities there that he expects to spend the rest of his life in prison.

Norwegian law allows for a convict to spend more than 21 years locked up under certain circumstances, if a court deems the prisoner dangerous enough to keep behind bars for additional five-year stretches, AFP reports.

"But how many times will that happen?" Daniel de Francisco, a 25-year-old chef said.

Norwegian law professors, meanwhile, told The Daily Caller that they are proud of the county's lenient judicial system and hope it does not get altered in the wake of Friday's mass killings.

“I think it is very important to keep it that way, despite the gruesome events that have occurred now,” professor Thomas Mathiesen of the University of Oslo told the website. “Norwegian society will gain nothing from a higher punishment level. People of this kind will not become less prone to engage as this man did ... and the punishment level we have now will contribute to Norway staying the relatively humane society that we are proud of and want to live in.”

Another Oslo law professor, Nils Christie, told The Daily Caller that many Norwegians are proud to live in a country that emphasizes moderation in retribution.

"I hope, and believe, that we also this time will be able to stick to our ideals of moderation in punishment," Christie said told the website. "The preliminary reactions to these days of horror in Norway have been exposure of a strong urge to live up to our basic ideals of remaining an open welfare society based on humanity." 

The Associated Press contributed to this report.