The kind of AK-47 that Mixon used to kill Oakland police officers Saturday can be had on the street for as little as $400.
Often they come from Nevada, where selling assault rifles is perfectly legal, unlike in California. Then they are brought to the Bay Area and resold.
If the buyer has a criminal past, "they have a friend - usually a girlfriend with no record - buy three or four," said one San Francisco narcotics cop who didn't want his name used because the department has not cleared him to speak publicly.
"Sometimes they all pitch in to buy them. Other times someone will go up, buy four guns, then come back and sell three of them to cover the cost of the one they keep."
"It's a right-to-your-door deal," the cop said.
Sometimes the crooks don't even bother with a middleman. Federal agents have a video from 2005 of a suspected West Sacramento gangbanger walking out of a Reno gun show with a newly purchased AK-47 strapped across his chest.
A source in the state Department of Justice told us the price of a semiautomatic assault rifle can jump significantly if the gun has been illegally modified to be fully automatic. But making the conversion isn't that tough.
"Sometimes it's done in garage workshops," the state source said. "It's a fairly simple procedure if you know what you're doing."
Once on the street, the guns are often moved from place to place, stashed in the home or apartment of a friend or relative - like a grandmother. "Someone without a record," our cop source said.
AK assault-style weapons are favored for their power and accuracy. They're good for turf fights.
"But they're pretty bulky," the cop said. "Smaller weapons are actually preferred by the pros, but they can cost twice as much."
The bulky AK assault weapons, however, are not losing their market share. Many are now being shipped south of the border for combatants in Mexico's growing drug wars.
Authorities say drug lords flush with cash are willing to pay twice the going rate for the weapons. Like most guns, AK rifles are illegal in Mexico, but the drug gangs can smuggle them in easily using their existing routes for narcotics.
Last year, the federal Bureau of Alcohol, Tobacco, Firearms and Explosives traced 7,500 weapons seized in Mexican drug raids - many them AK-47-type rifles - back to the United States, many of them from California.
"It's a big story," said Nina Delgadillo, spokeswoman for the agency's regional office. "You are talking about the type of firepower nobody wants to come up against."
Get out of jail free: In an effort to save money, California is exploring the idea of releasing thousands of offenders from prison without parole.
Only those convicted of a violent or other serious crime would be kept under watch.
The idea is meant to cope with the $400 million cut that the state Department of Corrections and Rehabilitation is taking in the new budget.
And although the change is just in the talking stages, it already has district attorneys worried.
"A felon caught with a gun is not considered a 'serious' felony," noted Alameda County District Attorney Tom Orloff.
Corrections department spokesman Gordon Hinkle said, "I don't know where any of these ideas are in terms of becoming reality, but we are looking at how other states handle parole.
"Whatever is decided," Hinkle said, "I'm sure it will also take legislative approval."
The mayor and the minister: San Francisco Mayor Gavin Newsom has a new co-star in his statewide gubernatorial campaign road show - Nation of Islam minister Christopher Muhammad.
For more than two years, Muhammad and his followers have been at odds with the city over their concerns that developers are kicking up asbestos-laden dirt out at the old Hunters Point Naval Shipyard, which is now in the city's hands. The local Nation of Islam has a school nearby.
The city insists there's no health risk. But Muhammad isn't buying it.
Muhammad and his Nation of Islam troops showed up en masse across the bay a couple of weeks back for the mayor's town-hall meeting in Oakland. Newsom tried to change the subject, but Muhammad and his people repeatedly shouted him down.
Newsom got an earful from some of Muhammad's followers a couple of nights later in Napa. He even promised to sit down with the Nation's leadership if only they would let the rest of the audience get some questions in.
No meeting, however, ever took place.
Newsom was again met by a San Francisco contingent at a town-hall gathering in San Diego last week, though Muhammad himself was not present.
Newsom has downplayed the fuss, but his handlers have a queasy feeling they'll be hearing more from the minister and his friends as the gubernatorial race heats up.
When it comes to San Francisco politics, says Newsom campaign manager Eric Jaye, "it's never over."
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This article appeared on page B - 1 of the San Francisco Chronicle