RICHMOND -- When gunshots ring out in Richmond, familiar scenes unfold. Calls to 911 and alerts from the city's ShotSpotter gunshot-detection system trickle in. Police cruisers scream to the scene. Detectives show up soon after.
But other detectives go somewhere else: to their computers to troll Facebook, Instagram, Twitter and other social media for clues, often provided by people involved in the crime who can't resist boasting.
"We have seen situations where someone will commit a shooting or a homicide, and they'll immediately write something on social media," said Matt Anderson, a Richmond gang detective. " 'Man down,' 'scoreboard,' those are the kinds of phrases they'll use, and it gives us a lot of clues about what just happened."
As social media increasingly have become an extension of who we are and how we communicate, it has emerged as a new battleground in the age-old struggle between Bay Area criminals and the detectives who seek them. Social media use is common among neighborhood crews and street gangs, who have inadvertently supplied police and prosecutors with troves of photos and other information often used to nab and then prosecute them.
Like braggadocio on a street corner or graffiti on a wall in yesteryear, gang members have come to use Twitter, Facebook, YouTube and Instagram to tout their criminal prowess, taunt rivals, boast about crimes and even gather information about potential targets of violence.
"What we see on social media brings an insight that you normally might not otherwise see," said Jeff Palmieri, a veteran gang investigator for the San Pablo Police Department. "You can get a view of who a person is, what they're about, and that not only helps us but can help a jury in a courtroom. Our intelligence information has grown by leaps and bounds in the last 10 years."
Online postings can help prosecutors establish a level of intent, premeditation, motive and gang affiliation, said Derek Butts, a Contra Costa deputy district attorney.
During the 2012 murder trial of Joe Blacknell, 23, Butts used the reputed Richmond gang member's MySpace account to prove to the jury that he committed numerous shootings in retaliation for the killing of his friend.
Among the evidence presented to the jury were photos of Blacknell holding an AK-47 assault rifle while dressed in a shirt memorializing his fallen friend, and private messages sent to rivals and friends boasting about the demise of Marcus Russell, an emerging Bay Area rap artist that Blacknell was convicted of murdering.
"The MySpace photos and messages were very revealing to jurors," Butts said. "It's one thing to have a gang expert testify about what the gang members say, but when you have the defendant's own communications, it paints a very compelling picture."
The same is true in San Jose, where Santa Clara County deputy district attorney Lance Daugherty, who supervises the gang unit, said more than a quarter of gang felony cases involve evidence gleaned from social media.
"It's such a widespread part of how we communicate today. Often, we get information about defendants who aren't even on social media themselves, but their fellow gang members may talk about that defendant or post pictures of them to their own accounts," Daugherty said. "They know this information is being used in prosecutions, but they still do it; it's part of their identities."
Assistant Contra Costa County district attorney Tom Kensok estimates that evidence from social media factors into more than half of the county's gang trials, although that number may be on the decline.
"In the beginning, a few years ago, it was often the equivalent of making a key find in a search warrant," he said. "Back then, they never had a sense that these postings would end up in a courtroom, that they were far from the law. Now, that advantage is gone."
The advantage was key a few years ago to trials involving members of Varrio Frontero Locos, a subset of the Sureño gang, who committed a string of homicides in San Pablo.
"The gang members were driving around, hunting rivals," Palmieri said.
When a half-dozen members were arrested and sent to trial, Palmieri was a key witness, testifying to juries that the killings were done to advance the gang's interests. He used photos from defendants' Facebook pages to prove it.
"Their own pictures showed them flashing gang signs, alongside other gang members, and holding guns," Palmieri said. "The average sentence was 55 years to life."
The cat-and-mouse game online is endlessly complex and in constant flux. Amid the infinite realm of the Web, images and words, often in coded language, circulate throughout cyberspace. MySpace was a platform of choice among Bay Area gang members a few years ago but was overtaken by Facebook and YouTube.
Instagram is now en vogue, thanks to looser restrictions on identities and a platform that is more image-driven and esoteric in its messaging.
"Instagram's popularity is a challenge," Anderson said. "It's harder to identify people; the messaging is more coded."
During an investigation last year that netted 11 arrests, including for charges of attempted murder, Anderson and his colleagues conducted extensive social media surveillance, and they discovered that the targets of their investigation were using social media to track rivals and plot attacks.
"Our investigation revealed that gang members will plan assaults based on disrespect of each other taking place on the social media," Anderson said. "They are pretty much doing the same thing we are doing, peeking around the social media accounts to gather information."
"Cyberbanging," as the communication is sometimes called, has become a key way for rival Richmond neighborhoods to lob slights at one another and communicate with cohorts. YouTube is awash with hundreds of hip-hop music videos -- ranging from amateurish cellphone recordings to slick, nearly professional-grade productions -- featuring young men representing various neighborhoods, brandishing guns and firing off challenges to rivals.
Gang members use Instagram and its photo-filtering apps to show themselves throwing hand gang signs, consorting with attractive women and brandishing high-powered weapons.
Regardless of the platform, social media posts often are followed with long chains of dueling rhetoric and threats, in constantly evolving language. Guns are referred to as "choppas," rivals as "suckas," and "scoreboard" can indicate that someone has just gunned down a victim.
Anderson and Palmieri declined to say whether they use fake social media profiles to infiltrate suspected gang members' social circles, but detectives in other jurisdictions have acknowledged the practice.
"I probably spend more time on social media than an average teenager," Anderson said. "It's my job."
Contact Robert Rogers at 510-262-2726. Follow him at Twitter.com/sfbaynewsrogers.