What happened, according to court documents and other sources:
At about 9:00 p.m. on January 11, 2005, 55-year-old Gurdeep Kaur was dropped off on Moraga Boulevard, across the street from her home near Lafayette, Calif. She was on her way back from Terzetto Cuisine, an Italian restaurant that her family owned where she worked as a cook. Kaur began to cross the street--although not in a crosswalk, which was 1,000 feet away--and was wearing a white sweater and black pants.

She was struck by a car and killed. The driver left the scene, and police found no skid marks. Kaur was taken to a hospital and died of what a coroner would later rule to be "multiple blunt force injuries" caused by the impact.

Moraga police announced that the vehicle was a red or burgundy Jaguar XJ6 or XJ8 built between 1995 and 2003, based in part on debris at the scene including a hood ornament that snapped off as a result of the impact. They asked the public for leads.

Eventually their investigation led them to secure a warrant to search the home of Lee Harbert, a San Francisco Bay-area investment banker who had been convicted three times for driving while intoxicated. (Apparently at least some convictions had been expunged.) Inside his garage was a black 2000 Jaguar Vanden Plas that had been recently cleaned. It had body damage and police found one of the dead woman's earrings in the windshield well.

It's undisputed that Harbert was the driver who hit and killed Kaur that evening; the question is whether or not he violated the vehicle code requiring a driver involved in such an accident to stop and provide assistance to an injured person.

Harbert claimed he believed he hit a deer. He had consumed three drinks in Marin County during a long meeting earlier in the day and was driving home. He described the incident thusly: "And I looked...down the road, I looked immediately northbound, because I knew whatever had struck the car was large. I had no idea at the time what it was. God forbid that it was a person. Whether it was a large animal or... not... I didn't know." Also, because the police were looking for a red and burgundy Jaguar, he claimed to believe his accident was unrelated to the hit-and-run.

This could have remained a he said/she said situation except for a detail that makes this case relevant to Police Blotter: Harbert's Internet searches.

When police searched Harbert's house, they examined his computer. They found evidence of Google searches a few days after the accident for search terms including "auto glass reporting requirements to law enforcement," "auto glass, Las Vegas," auto parts, auto theft, and the Moraga Police Department. He allegedly also searched for "hit-and-run," which led him to a Web page dealing with the death of Kaur that said police had a lead on the vehicle.

During the trial, the prosecutor told the jury: "And I think what he did afterwards is extremely telling, also, the computer searches and Web pages. Auto parts, auto dealers out-of-state; auto glass, Las Vegas; auto glass reporting requirements to law enforcement, auto theft... The defendant didn't offer you any explanation for the auto theft, one, and he had a series of excuses for the other ones. But when you put them all together, the only reasonable conclusion was he was going to try to get the car fixed somewhere else far away so he wouldn't be found out, he was going to try and avoid having anything reported to law enforcement."

Harbert was convicted and sentenced to three years in prison, with the trial judge lecturing him for a "display of arrogance and self-absorption... while you were on the stand." He appealed, saying that the prosecutors' arguments amounted to misconduct and that there was no evidence he had actual knowledge a person was hit. A California appeals court rejected his arguments this week.

This isn't the first time that police have used Google searches to nab suspects. Police Blotter has chronicled a 2006 case involving a wireless hacker ("how to broadcast interference over wifi 2.4 GHZ") and a 2008 case involving a woman convicted of murdering her husband ("decomposition of a body in water"). Searches in a 2005 murder case included "neck," "snap," and "break."

Police Blotter: Google searches nab hit-and-run driver | Politics and Law - CNET News
I did some "googling" of my own to see more on what this was about.
Whether the guy knew he had hit a person would be irrelevant to whether or not he committed voluntary or involuntary manslaughter.

But in California, there are explicit laws regarding what a person is to do in a "hit and run" situation, presumably above and beyond the "manslaughter" charges.
Hit and Run Laws in California

Also, the actions of the motorist afterwards would be utilized in sentencing, and an attempt to cover up the crime would expectedly raise the resulting punishment.

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This is the exact reason I haven't killed anyone yet...

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