Seoul prosecutors on Tuesday raided police and municipal offices in an investigation into the Halloween tragedy in Itaewon, a neighborhood in the capital city’s central district of Yongsan.

The searches took place at the headquarters of the Seoul Metropolitan Police, the district police and the office of Yongsan, prosecutors said.

The prosecutors also searched the detention center where some of the key suspects are detained.

Police on Nov. 1 set up an independent team to investigate the disaster in Itaewon, and after nearly two months of investigation, sent the heads of the Yongsan district police and municipal office to prosecutors.

At the parliamentary investigation, launched in November, the police were grilled over their failures in crowd management and slow responses at the time of the disaster.

Prosecutors opened the investigation into death and injury by occupational negligence and other charges alongside the police investigation.

On Oct. 29, a crowd crush of mostly young people celebrating Halloween in a narrow alley in Itaewon led to 159 dead and 195 injured.