Man told building residents they were 'going to pay' before setting structure ablaze, killing veteran firefighter: Police

Inset, left to right: Sheaves Slate (CPD) and Michael Altman (CFD). Background: The area in Chicago where Slate allegedly started the fire that killed Altman (WLS).

A 27-year-old man in Illinois is accused of killing a veteran Chicago firefighter after he allegedly set fire to a mattress in a basement boiler room of his former apartment building, blocking access to the blaze and walking away without warning anyone inside.

Sheaves Slate is currently facing charges of first-degree murder, aggravated arson, and residential arson in connection with the deadly fire that killed firefighter Michael Altman.

Prosecutors say the fire came hours after a confrontation with residents, during which Slate was overheard making threatening remarks, including telling the residents they "are going to pay," local Fox affiliate WFLD reported.

According to court filings, Slate previously lived in the building but had moved out about nine months earlier. However, he reportedly returned to the building frequently, using a broken window to illegally stay in the basement near the boiler room, local ABC affiliate WLS reported.

In the days leading up to the fire, several tenants reported seeing him inside restricted areas of the building despite being told to leave.

On March 15, Slate allegedly demanded to see a former roommate, but became angry when he was not allowed into the building. During the confrontation, Slate allegedly said the tenants "are going to pay" for crossing him.

One tenant even called 911 during the disturbance but quickly canceled any law enforcement response after believing Slate had left, local PBS affiliate WTTW reported. Surveillance footage and witness accounts indicate he remained in the building overnight, at one point sleeping in a hallway.

At about 4 a.m. on March 16, several hours after the canceled 911 call, another resident reportedly spotted Slate in the building and ordered him to leave. The defendant left, but soon reentered through the broken basement window, spending hours inside the boiler room. There, he allegedly used a lighter to set a mattress on fire. When the flames grew, he positioned a door in front of the room — a move investigators say concealed the fire and delayed discovery — before leaving without calling for help.

Smoke began spreading through the building shortly before 11:30 a.m., prompting multiple 911 calls.

Responding crews included Altman, a 32-year-old Chicago Fire Department firefighter assigned to Truck 47. Prosecutors say firefighters in the basement moved the door blocking the room, triggering a collapse of the first-floor structure above them.

Altman, who was operating on the first floor, fell into the basement and was engulfed in flames. He suffered burns to 90% of his body and died the following day.

After leaving the scene, Slate allegedly took public transit to the Harold Washington Library, where he changed clothes and dyed his hair. He later checked himself into a hospital for suicidal thoughts, where he was taken into custody.

Prosecutors say Slate ultimately admitted to starting the fire, telling investigators he acted while depressed and suicidal.

A judge described Slate as a threat to the community, citing allegations he has a "penchant for setting fires" while also noting his prior legal issues and an outstanding warrant at the time of the blaze, WLS reported. The judge ultimately ordered Slate to be held in custody without bond.

"We are all grieving the tragic loss of Michael Altman — a young father and dedicated firefighter who followed in his family's footsteps to serve and protect others," Cook County State's Attorney Eileen O'Neill Burke said in a statement. "His death is a profound loss for the Chicago Fire Department, his family and loved ones, and communities across Cook County."

Altman, a fourth-generation firefighter, is survived by his wife and a young child, with another child on the way. Chicago Mayor Brandon Johnson called him "not just a public servant, but a true hero," praising his "courage, bravery, and strength" in the line of duty.

Slate is currently due back in court April 8.