California Watch’s Corey Johnson was scanning the website of the state architect’s office one evening in December 2009 when he noticed something strange. The state was changing the status of schools with building projects lacking seismic safety certification, downgrading the severity of the violations “in bunches” without ever visiting the schools, as Johnson tells it.

It didn’t take long to connect the dots. Johnson was three months into an investigation of earthquake safety at California schools and had recently asked for a previously undisclosed list of those with potentially unsafe buildings. A couple days after noticing the changes taking place at the state architect’s website, Johnson obtained minutes of an internal meeting in which state managers warned, “Sensitivity has increased as to reporters digging deep into government business. People need to be mindful of what they put into emails.” Elsewhere they urged, “We need to figure out why Los Angeles has so many Type 4 letters,” referring to the most serious violation of the Field Act, a 1933 law mandating strict oversight of earthquake resistant construction at K-12 schools and community colleges.

Discovering the changes was an “a-ha moment” for Johnson, and just one of many breakthroughs in an meticulously documented investigation that revealed at least 20,000 projects, “from minor fire alarm upgrades to major construction of new classrooms,” that were completed without Field Act certification. What began for him as a “quick turnaround” story about the twentieth anniversary of the 1989 Loma Prieta earthquake in San Francisco Bay Area ultimately turned into a nineteen-month project that involved nearly four dozen staff members and freelance contributors, as well as California Watch’s partners at KQED Public Radio.

California Watch—a project of the Center for Investigative Reporting launched in the summer of 2009—began releasing the multimedia series, titled “On Shaky Ground,” on April 8 in coordination with a suite of newspapers, public radio and television stations, ABC news affiliates, sites, and foreign-language newspapers statewide. Three articles form the backbone. Part 1 describes the lax oversight of seismic safety at schools, the history of the regulatory system and how it broke down over time, and cases of specific schools lacking safety certification. Part 2 reveals that many special seismic safety inspectors, hired by school districts and trained in the Field Act, are still reviewing building projects despite histories of poor performance. And Part 3 explains how restrictive rules have kept California schools from accessing a $200 million fund approved by voters in 2006 to shore up seismically unsafe buildings.

“It’s been a bear,” Johnson said in an interview describing the effort. “It’s an incredibly complicated story with a lot of moving parts and technical details, and the government was not that interested in talking straight or clear, so there was a lot of work—a lot of historical work, even—that went into figuring out what the procedures and policies were, and what they really meant, so that I could appropriately interpret what was being said by state officials and school district people, because there’s a lot of spinning that goes on in a story like this.

“I’m trying to avoid the clichés you hear when reporters tell these kinds of stories, but it really was brick-and-mortar. Somebody tells you a piece of information, you try to verify it, and it goes from there. Ultimately, I started to work on multiple fronts, trying to pull together all of this information, understand it, and deal with the various agencies who, once it became apparent to them that they were the focus of an investigation, got really difficult to deal with. They started saying that things didn’t exist, and I found that they did, and they started telling employees not to talk. It was just the whole gamut of things that happen in America when people think they’re under investigation, which they were.”

California Watch produced an excellent, step-by-step timeline of Johnson’s investigation, complete with a rolling document counter that rises to over 30,000 by early 2010, but it is even more interesting to hear Johnson tell the story in his own words. After he learned of the state’s list of schools lacking seismic safety certification, which hadn’t been released publically, a staffer on the state legislature’s education committee said it would be hard to get details, but pointed him to the Division of the State Architect, which oversees compliance.

“Those two bits of information—that there is a list that the state doesn’t want anybody to have and that some schools might not comply with the Field Act—were the two things that got my juices flowing,” Johnson said.

Curtis Brainard writes on science and environment reporting. Follow him on Twitter @cbrainard.