The NTSB issued a probable cause today. In part, Quote
Washington, DC - The National Transportation Safety Board
today determined that the probable cause of the crash late
last year of a Raytheon (Beechcraft) King Air 100 airplane,
carrying Senator Paul Wellstone and seven others, was the
"flight crew's failure to maintain adequate airspeed, which
led to an aerodynamic stall from which they did not
recover."
Reviewing the results of the extensive investigation into
this accident, NTSB Members concluded that the flight crew
failed to maintain an appropriate course and speed for the
approach to Eveleth and did not properly configure the
airplane at the start of approach procedures.
"During the later stages of the approach," the Board said,
the flight crew "failed to monitor the airplane's airspeed
and allowed it to decrease to a dangerously low level (as
low as about 50 knots below the company's recommended
approach speed) and to remain below the recommended approach
speed for about 50 seconds." The airplane then entered a
stall from which it did not recover.