A case credited with shedding light on a tendency within the medical community to cover up malpractice has taken another step into uncharted waters.

A little over a year after the death of Etsuko Nagai at Tokyo Metropolitan Hiroo Hospital -- attributed to an intravenous drip of disinfectant -- police on Friday sent papers to the prosecutor's office to press criminal charges against Kiyoshi Okai, the former hospital director, and eight other doctors, nurses and hospital administrators.

The charges ranged from suspected negligence to alleged attempts to cover up the cause of Nagai's death in February 1999. None of the nine have contested the charges, police said.