Then another nightmare unfolded.
As Rosenberg investigated driver Roberto Galo's background, he discovered that San Francisco's sanctuary-city policies have served as an enabler for dangerous drivers.
Rosenberg sees his son's death as highly preventable. Five months earlier, San Francisco police stopped Galo for driving the wrong way on a one-way street and driving without a license. The city even impounded his Chevrolet -- the car that later would kill Drew Rosenberg -- which a friend recovered and then released to Galo.
I write "even impounded" because, though it is illegal to drive without a license, in 2009 then-Mayor Gavin Newsom implemented a policy to allow unlicensed drivers stopped by police to avoid an automatic impoundment of their cars if a licensed driver could drive them away. Police Chief (now the district attorney) George Gascon told the San Francisco Chronicle's Phil Matier and Andrew Ross, "We recognize that this is a problem within the Hispanic community, where people working here can't get a driver's license because of their immigration status."
At the time, Gascon told me the policy should not be seen as a get-out-of-jail-free card, because "we're stopping them from driving." The policy, he argued, replaced unlicensed drivers with licensed drivers. And it would prevent unlicensed drivers from trying to flee the scene of an accident.
That's an important point. The district attorney's office charged Galo for driving without a license and felony negligent homicide -- a felony because witnesses testified that, with his wife and kids in the car, Galo had backed over Drew Rosenberg's body.
In 2009, Gascon also told me that Newsom's policy was put in place not to help illegal immigrants, who are ineligible to get a license, but to help all residents who cannot afford to get a license or driver's training. The idea was to help all unlicensed drivers. A 2008 study by the AAA Foundation for Traffic Safety found that 29 percent of fatal crashes in California from 2001 to 2005 involved unlicensed or improperly licensed drivers. So -- why?