Jurors late Monday afternoon acquitted 44-year-old Carlos Siordia of driving a vehicle in the commission of an unlawful act, one of two misdemeanor vehicular manslaughter charges he faced as a result of the Sept. 22, 2008, crash that killed 9-year-old Tyler Fahy.
The jurors said Monday that they were unable to reach a consensus on the other misdemeanor vehicular manslaughter charge, which was based on criminal negligence.
Judge Mark Forcum questioned each juror and four said they believed additional legal instructions might aid in their deliberations and possibly help them reach a verdict on the first count.
He then instructed them to continue deliberating, which they did until 2 p.m. today when they advised the court they were hopelessly deadlocked.
The case was continued until April 6 for the prosecution's decision on further proceedings.
Chief Deputy District Attorney Steve Wagstaffe said the district attorney's office was disappointed with the outcome, but acknowledged the case was challenging.
"The jury spent a long time struggling with it," Wagstaffe said. "We know it was a very difficult decision, and while disappointed we understand the difficulty they went through."
Siordia was driving a construction truck that plowed through the intersection of Olympic and 43rd avenues in San Mateo and struck a sport utility vehicle at about 1:15 p.m. on Sept. 22, 2008.
Both vehicles then traveled into the Mollie Stone's parking lot and hit seven other cars and a pedestrian.
Tyler, who was a passenger in the SUV, died at the scene. His mother and two other women were injured.
Siordia has maintained that the brakes on the truck didn't work, and his defense attorney John Elworth said during his closing arguments that Siordia was consistent in his interviews with police.
During his closing arguments, prosecutor Michael Wendler pointed out two possible theories to the jury as to offenses Siordia may have committed.
The first theory is that Siordia committed "an unlawful act with ordinary negligence" causing death, and the second is that Siordia committed an infraction, such as speeding or coasting, causing death.
Elworth, however, told jurors that the prosecution's inability to pinpoint a specific crime indicated that his client was not guilty.
Siordia has been out of custody on a $25,000 bail bond.