Chicago police may be one step closer to finding the person to blame for a fire in the city's Austin neighborhood that killed four people, including a child.

Alderwoman Emma Mitts, who represents the 37th Ward, said detectives know who they are looking for an arrest is only a matter of time.

A pregnant mother, her 5-year-old son, her younger sister and a well-known journalist were all killed in the fire in the 5200 block of North Avenue in the early hours of last Thursday morning.

The fire broke out just before 2 a.m. on June 26. Chicago firefighters used at least eight ladders to bring residents to safety. Some had to escape by stairs or jumping from the building.

Police investigated the first as suspicious from the start, with the assistance of the Bureau of Alcohol, Tobacco and Firearms. Witnesses said someone threw a Molotov cocktail through the window.

Investigators said they believe the fire was started during or after a domestic incident, though they have not said who was involved.

The four people who died were identified as 32-year-old Regina Henry, her 5-year-old son Jayceon Henry, and her28-year-old sister Destiny Henry, who went back into the burning building after her 4-year-old who she didn't realize had already been rescued, as well as 76-year-old Brad Cumming, editor of the Austin neighborhood The Voice newspaper. 

• Austin
• Chicago Fire Department
• Fire