KENNEWICK, Wash. -

Investigators believe a man was driving at least 72 mph in a 40 mph zone in Kennewick when he struck and killed a pedestrian.

Michael S. Johnson was charged Thursday with vehicular homicide in the April crash that killed 52-year-old Nina Howard of Kennewick.

The Tri-City Herald reports Johnson said he didn't know how fast he was driving because the speedometer was broken.