[Bernard]

Authorities began inspecting close to 40 murals, which comprise tens of thousands of individual tiles, when the San Francisco Unified School District notified authorities after Norris' arrest

So somebody knew about it before his arrest, and didn't say anything? Sounds like another story, if there is an investigative reporter available in San Fran.

[GSWarrior]

So somebody knew about it before his arrest, and didn't say anything?

Perhaps. His arrest could have raised a red flag with school officials, however, prompting them to look into the matter.