SAN JOSE -- A Gilroy man and two-time DUI offender was convicted of murder for a drunken driving crash three years ago that killed a 4-year-old boy on Highway 101 in South San Jose, authorities said.

A jury found 46-year-old James Francis Lee guilty Monday of offenses including second-degree murder and gross vehicular manslaughter while intoxicated in the July 11, 2010, death of Jose Diaz as his family awaited for help with their disabled truck in the southbound lanes near Bailey Avenue.

Lee, a truck mechanic and San Jose native, is scheduled to be sentenced Sept. 23. He faces a maximum sentence of 21 years to life in prison.

"This wasn't an accident, this was a crime," prosecutor Angela Bernhard said. "Here is a defendant who has more knowledge than the average person regarding the dangers of drinking and driving. When he made a choice to drink and drive again, killing Jose -- the law calls that murder."

On evening of the crash, Lee was seen "wildly" swerving his Ford F-150 across southbound Highway 85 and later onto Highway 101.

A short distance away, near Bailey Avenue, Jose was asleep in the back of a Chevy pickup that broke down on the side of the road. His father, Jesus Diaz, was in the vehicle checking on his young son while Jose's mother and sister waited outside on shoulder.

That's when Lee's vehicle smashed into back of the Diaz family truck, knocking the father out of the way and driving a mounted toolbox into the child's head. A rescue helicopter landed directly onto the freeway to whisk the boy to the hospital, where he died from his injuries.

The boy's father was seriously injured but survived. According to first responders, the Chevy was so smashed in that they initially thought the truck was a hatchback.

After the crash the California Highway Patrol determined that Lee's blood-alcohol level was .17 percent, more than twice the legal limit. He told officers he had been drinking beer after attending a concert at Shoreline Amphitheatre. He also had two prior DUI convictions.

During his weeklong trial Lee unsuccessfully argued that the child died because he was unrestrained and that the toolbox had been shoddily mounted to the truck.

Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga.