My client has admitted to having handed out punches. But it was not his intention to kill, says the man's lawyer Jonas Kirschon to the newspaper.
The man has been arrested on probable cause suspected of attempted murder.
Earlier, Aftonbladet reported that the police had an ongoing surveillance operation against the man.
The injured party, a man in his 60s, was unknown to the perpetrator. He was taken to hospital by ambulance. His injuries were not considered life-threatening.
On Thursday, the now-arrested man was released after a longer prison sentence for a serious violent crime. According to Aftonbladet's information, it was deemed that there was a high risk that the man would commit new violent crimes in order to be arrested again and thus get a roof over his head. Therefore, an operation was initiated to prevent this.
The police's press secretary Mats Eriksson confirmed to Aftonbladet that the operation was carried out to observe him and keep an eye on him.
"In this case, there are different circumstances that meant we could not prevent the crime," Eriksson writes in an email to the newspaper.
The arrested man has a long history of mental illness, according to Aftonbladet. He was sentenced to forensic psychiatric care in the 1990s for several violent crimes.