No contest plea in fatal Pleasanton crash that killed cyclist

A 19-year-old pleaded no contest Thursday to vehicular manslaughter in connection with a crash that killed a bicyclist in Pleasanton, ending what had once been a murder case because the man had boasted about speeding on Twitter.

Cody Hall entered his plea in Alameda County Superior Court in the death of Diana Hersevoort, 58, of Dublin, who was struck along with her husband on June 9 while pedaling north on busy Foothill Road, south of Golden Eagle Way.

Hall is expected to be sentenced in May to nine years in prison.

An analysis of his driving record and pattern - along with Twitter posts in which he talked about how fast he liked to drive - factored into a decision by Alameda County prosecutors to upgrade the charge against him from vehicular manslaughter to murder, authorities said.

But a judge later reduced the charge to vehicular manslaughter.

According to police, Hall was driving north in a 2004 Dodge Neon and was traveling 83 mph in a 40-mph zone as he passed a vehicle about 1 p.m. He lost control and crashed into the couple, killing Diana Hersevoort and injuring her husband, Johannes Hersevoort.

Henry K. Lee is a San Francisco Chronicle staff writer. E-mail: hlee@sfchronicle.com Twitter: @henryklee