Police plan to soon raid the Tokyo headquarters of Schindler Elevator K.K. over an accident in which a woman was crushed to death in Ishikawa Prefecture last week, investigative sources said Sunday.

Investigators suspect professional negligence was to blame in the death of a cleaning woman who became wedged when one of the company's elevators began to ascend with the doors open at a hotel in Kanazawa on Wednesday, the sources said.

Police have already raided the Nagoya office of Shindler Elevator, the Japanese arm of Swiss-based Schindler Holding Ltd., as well as a maintenance firm in Kanazawa on suspicion of professional negligence.

Toshiko Maeda, 63, a resident of Nomi in Ishikawa Prefecture, was crushed to death in the accident at Apa Hotel Kanazawa-Ekimae, where she worked as a part-time employee for a cleaning company.

Her funeral was held Sunday morning in Nonoichi, Ishikawa Prefecture. Ryushi Iida, service division director at Schindler Elevator, visited the funeral hall but was immediately sent packing by Maeda's grieving relatives.

Maeda was entering the elevator when it suddenly began to ascend with its doors open, pinning her between the floor and entrance frame as it moved up the shaft.

Schindler Elevator's Iida told reporters that the company will renew its attempts to meet with the family to offer its sincere apologies for the accident, adding an internal investigation into the causes is already under way and will examine every aspect, from the elevator's braking system to current inspection procedures.

The hoisting machinery and braking and control systems of the elevator in the Kanazawa hotel were the same as those that caused the 2006 death of a 16-year-old boy in a Tokyo condominium, in a similar accident involving one of the firm's elevators, sources at Schindler Elevator said earlier.