A 52-year-old man from Illinois is facing charges of involuntary manslaughter following an event last month that resulted in the death of a 9-year-old boy at a Chicago Transit Authority station.

Police announced the arrest of Michael Korosa on Monday, WMAQ reported.

According to investigators, 9-year-old Elijah Flores was departing a train with his mother’s boyfriend shortly after 11 a.m. on August 10. At the Clinton Station, an argument broke out between the boyfriend and two other men, leading the two men to chase the boyfriend and Elijah from the platform.

The 22-year-old boyfriend picked up Elijah because the child was struggling to keep pace, as noted in a police report. During the chase, one of the two men struck the boyfriend in the back with an “object,” causing both him and Elijah to tumble down a set of stairs. The boyfriend fell on top of Elijah, causing the child to lose consciousness and suffer a skull fracture.

Elijah was transported to Lurie Children’s Hospital in critical condition and passed away six days later. The Cook County Medical Examiner’s Office determined that the boy died from blunt force trauma to the head, classifying his death as a homicide.

Korosa was identified as one of the two men involved in the confrontation with the boyfriend. Originally, he was charged with murder when apprehended on Sunday, according to WGN, but by Monday, the charges were reduced.

Korosa was also charged with aggravated battery.

Police did not say what the men were arguing about or whether they had identified the second man involved and if he would also face charges.