Investigators have determined that the Allston fire that killed a Boston University student last week was caused by the careless disposal of smoking materials, the Boston Fire Department said today.

The department said it based its conclusions on the burn patterns inside the three-story house at 87 Linden St., interviews with the former residents, and physical evidence collected by fire investigators.

Binland Lee, 22, a marine sciences major from Brooklyn, NY, lived on the third floor and was fatally injured during the fire.

Investigators concluded the fire originated near an interior staircase, the department said.

“Specifically, it started in the area of an interior staircase that was permanently blocked off on the first floor but was an open space to those using the stairs to the second floor from the rear of the house,’’ the statement said.


A fire that eventually needed a three-alarm response to bring under control was reported at 6:35 a.m. on April 28.

The city’s Inspectional Services Department cited landlord Anna Belokurova, a Newton resident, for running an illegal rooming house after authorities concluded 19 people were living in what was supposed to be a two-family home.

The city had not inspected the property since 1992, officials said this week.

Suffolk District Attorney Daniel F. Conley’s office is continuing its inquiry into the circumstances of the fire, but prosecutors have not yet concluded whether to bring criminal charges against Belokurova or anyone else.