Authorities have arrested ten debt collectors for suspected involvement in the controversial case of a man sentenced to life in prison for killing a loan shark's henchman, who engaged in lewd acts at the convict's mother to threaten her into paying a debt.

Gang leaders Wu Xuezhan and Zhao Rongrong, Wu's accountant, have been in custody for six months. The matter has been handed over to the local procuratorate of Liaocheng, East China's Shandong Province, who has been assigned to prosecute the case.

Yu Huan, 23, was sentenced to life in prison in February for using a fruit knife on four of 11 men sent to collect a debt. The men cornered him and his mother, Su Yinxia, 48, in April 2016.

The case generated a lively discussion on Chinese social media on whether Yu's sentence was too harsh or if police were negligent, following media reports that the local police were called to the scene shortly before the tragedy but did not stop the debt collectors from using force.

On Monday, Su's brake pad factory was deserted. It employed about 60 workers before being closed in December 2016.

The Higher People's Court of Shandong Province agreed to hear Yu's appeal, which was filed on February 24. On Monday, the higher court summoned Yu's new lawyer, Yin Qingli, to review case files as they prepare for the trial of the second instance, the date of which remains to be set.

Yin told the Global Times that Yu was actually practicing "self-defense" with the knife, and that Yu surrendered to the police after hurting the four men, which the court should consider. Yin said he will try to convince the court to reverse Yu's earlier sentence.

The incident began when Yu's mother borrowed 1.35 million yuan ($195,964) from Wu with a 10-percent monthly interest between 2014 and 2015. Su paid back 1.84 million yuan in cash and gave Wu a property worth around 700,000 yuan, but still owed Wu about 170,000 yuan when the men were sent to collect the money from Yu's office on April 14, 2016.

Yu Xiurong, Yu Huan's aunt, told the Global Times that the henchmen called Su a whore and beat her son. One of the debt collectors, Du Zhihao, exposed himself to Su, Yu said.

Liaocheng police detained Wu and two others in August 2016 for allegedly running mafia-like gangs, thepaper.cn reported. However, adding to the complexity of the case, police detained Su in December 2016 for allegedly "raising funds by means of fraud."