Prosecutors in the appeal of a young man who had been sentenced to life in prison for intentionally causing injury said his behavior fit the legal definition of excessive self-defense when the case was reheard over the weekend.

The Supreme People's Procuratorate posted a statement on Sunday saying that Yu Huan's actions in the stabbing case were a kind of self-defense, "but obviously excessive".

Twenty-one-year-old Yu was convicted on Feb 17 for stabbing four debt collectors who confronted him and his mother. One of the debt collectors later died.

Yu appealed to the Shandong Provincial High People's Court, claiming he attacked the debt collectors with a knife because one of them insulted his mother by exposing himself to her.

The appeal hearing in this controversial case was held on Saturday at the high court.

Yu, from Guanxian county in Liaocheng, Shandong, said he and his mother, Su Yinxia, were confronted on April 14, 2016, by more than 10 debt collectors because they were unable to repay loans.

"I felt helpless when the debt collectors assaulted and insulted my mother and me. If I had not used a knife to defend us, I and my mother would have fallen into a more dangerous situation," he said.

Yu's lawyer said it was justifiable defense, as the stabbings were done in an attempt to protect himself and his mother.

But the provincial prosecutors said Yu's attack had caused the death of one person and serious injury of two others, "which meets the standard of serious damage and excessive self-defense, as defined by the Criminal Law."

The case was widely discussed on social media, with some saying Yu's life sentence was too harsh and some criticizing how police officers had handled the incident.

Yu had said that when the police left him and his mother with the debt collectors while they gathered information, he thought they had abandoned the case.

On March 26, the top prosecuting authority dispatched prosecutors to Shandong to oversee the case and investigate whether the police had been derelict in their duty.

On Friday, the provincial prosecutors released a report that said police involved in the case had failed to effectively control the scene and failed to separate the debt collectors from Yu and his mother, but that their behavior did not meet the legal standard for dereliction of duty.

The police officers who responded to the incident and some senior officials at the police station who were involved in the case were given disciplinary punishments.

More than 100 people heard the appeal, and the court posted the proceedings on its micro blog.

The judges did not announce a verdict in the courtroom.

caoyin@chinadaily.com.cn