The hacker group Anonymous made good on a promise to erase online traces of the man accused of committing a deadly terrorist attack in Norway last month by hacking into his Twitter account over the weekend.

Initial Tweets sent from the hijacked account on Sunday afternoon had some followers believing Anders Behring Breivik was sending messages from prison. By Sunday evening a series of Tweets unraveled the mystery -- “This Twitter account has been seized by #NORIA. @AnonymousNorway” and “We want Anders to be forgotten. Labels like ‘monster’ or ‘maniac’ won’t do either” and “Media should call him pathetic; a nothing. #Forgethim” -- clearly, Breivik was no longer controlling the account.

On Sunday night, according to Mashable, a message said the account would be shut down. As of Monday afternoon, the account is still available but all messages -- including those presumably sent by Breivik before the attack -- had been deleted.

For awhile on Sunday the hackers left Breivik’s original Tweet on the Twitter page:: “One person with a belief is equal to the force of 100 000 who have only interests,” a quote from philosopher John Stuart Mill. It’s removal confused some people who had been keeping watch on the Twitter stream.

“wait..... why is @AndersBBreivik 's only tweet deleted?” one follower asked, while others questioned why anyone had chosen to follow the account in the aftermath of the rampage.

“SHAME ON EVERYONE WHO FOLOWS ‘AndersBBreivik’ on twitter! SHAME!!’” @MartinModel tweeted, while Nadia__Carvalho added “@AndersBBreivik has 3982 followers. what kind of psychotic people would follow him …”

Others moved quickly to spread the information that the account had been hacked and clear up confusion after the initial Tweets were posted Sunday afternoon, while others simply used the latest development as a chance to Tweet more anger over the incident:

“I fucking hate @andersbbreivik,” @jbfannorway1 posted on Monday.

Breivik opened the Twitter account just days before the attack that killed more than 90 people. A Facebook account that was linked to Breivik was deleted within days of the attack.

Anonymous had announced plans last week to find and rewrite the 1,500-page Breivik is said to have written prior to the attacks. As the group said at that time, “Let Anders become a joke, such that nobody will take him seriously anymore.”