The Oakland Police Department's forensic firearms lab is at the end of a hall on the sixth floor. You can count the number of technicians who work there on one hand. Or half a hand.
It's not "CSI." Their work is slow and meticulous: test firing weapons; peering through comparison microscopes at unique markings left on slender bullets, squashed fragments and spent shell casings left at crime scenes.
When criminalist Mark Bennett sends that information to a national ballistics database, he might find out it matches evidence collected in another crime. What he won't find out is where the guns he tests come from. And he is not alone.
National crime gun trace data is available to agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives, but federal laws passed by Congress within the past decade prohibit the ATF from releasing to the public detailed information on the results of ballistics tests and gun traces initiated by its own agents and law enforcement agencies around the country.
All but the most general information -- contained in a report published by the ATF once a year -- is off-limits to the public, politicians and academics.
"(The data was) threatening to the gun lobby," said Dennis Henigan, vice president of the Brady Center to Prevent Gun Violence. "It showed that a small percentage of gun dealers -- 1 percent -- accounted for 60 percent of the traced guns, which shows there were relatively few dealers who were facilitating crime guns."
Trader Sports in San Leandro, which in 2006 had its firearms license revoked by the federal government for numerous violations and has since closed that location, was one of them.
It wasn't always that way. Before the 2003 Tiahrt Amendment, named after former U.S. Rep. Todd Tiahrt, R-Kan., ¿the Clinton administration encouraged gun tracing and data sharing that helped educate the public and law enforcement about the types of guns used in crimes and where exactly they were coming from, Henigan said.
Information released by the ATF in 2000 revealed that slightly more than 1 percent of the country's licensed gun dealers sold more than half the guns recovered as a result of criminal investigations.
Academics and policy experts examined the trace data and revealed facts the gun lobby didn't want out there, such as the name of retailers who sold the majority of guns traced to crimes across the United States and to other countries.
The reaction from the National Rifle Association and other groups was quick and fierce.
NRA spokesman Andrew Arulanandam said trace data that was intended for use by law enforcement to solve and prosecute crimes was being misrepresented by politicians and gun control advocates to encourage the prosecution of gun companies for "criminal misuse of firearms."
He said academics were lumping traces for lost and abandoned weapons in with traces initiated on guns used at crime scenes and inflating the numbers.
"The public shouldn't have access to this (information)," Arulanandam said. "It was intended to be used for law enforcement, by law enforcement. There's no need for politicians to have it. The contention that (the law) hampers investigations is completely false. The statute says that any local, state, federal and international law enforcement will have access to trace information as part of a bona fide investigation."
The Tiahrt Amendment is often cited by gun control advocates as the law that most threatens public safety because it protects the identity of gun sellers and prohibits the ATF from divulging detailed gun trace data.
ATF gun trace data revealed that between July 1996 and April 1999 one gun store in Milwaukee was responsible for selling more than two-thirds of the crime guns recovered in that city within a year of sale, said Daniel Webster, professor and co-director of the Center for Gun Policy and Research at Johns Hopkins Bloomberg School of Public Health.
When the ATF publicized the data, the store stopped selling junk guns -- small, inexpensive handguns also referred to as Saturday night specials. The researchers were able to show that the number of new, recovered crime guns in Milwaukee substantially declined after the store made the change in policy.
"Our study showed what a tremendous impact that had on the flow of guns, not just in junk guns, but all guns," Webster said.
Henigan said the ATF gun trace data that was available to researchers before the Tiahrt Amendment showed a strong connection between the legal market and the illegal market for guns.
"The NRA is always saying gun control can't work, that criminals get their guns off the street from the black market, like they fell from the sky," he said. "But trace data was showing that the black market was being fed by the legal gun market, through secondary sales."
Oakland is lucky. Although there is a backlog of weapons awaiting ballistics testing, ATF agents who are collaborating with the Police Department's Gangs/Guns Intelligence Task Force handle the recovered gun traces. Put together, the ballistics results and crime gun trace data can build a substantial case.
Both Oakland Sgt. Nishant Joshi and Officer Kevin Kaney of the Gangs/Guns Intelligence Task Force say they rely on ATF to trace the flow of out of state guns into Oakland. Unless the federal agents tell them, they rarely know where those guns are coming from. And the information is restricted to Oakland investigations.
"The ATF will give Oakland trace data about Oakland's crime guns, but if (the department) wanted to know which dealers within 100 miles of Oakland were responsible for the most traces, it couldn't find that out," Henigan said. "Whereas before, Oakland could find out how many traces Traders (Sports) had and where those guns were used, no matter the county."