The quarry here was copper.
"They even take motors, I learned, from the elevator shaft," said LAPD Sgt. Robert Hernandez. "I was told they're worth like $300,000 each. I guess they're all made of copper."
The LAPD is investigating an elaborate operation they suspect was carried out by a whole ring of thieves.
Under arrest for burglary, 50-year-old David Garner was found hiding above a false ceiling, sniffed out by a K-9 unit.
Police say it is possible that an alleged accomplice is still holed up in a 12-story maze of crawlspaces.
"It seems that they even set up camp and plan on staying, could be for days, weeks at a time," said Hernandez. "They turn off electricity, they reconstruct their own electricity. They cut pipes."
It's a persistent problem downtown where many buildings sit empty.
It is more than private buildings targeted. Thieves also plunder public utilities. They can break through a light pole and inside find 30 feet of copper wiring.
Investigators hope to identify some of the loot at local recycling centers where the law now requires picture identification.
The metal industry is also stamping more copper parts with serial numbers.
"A lot of it is marked," said LAPD Officer Jack Richter. "A lot of it has identification marks on it and detectives will find where this has gone and backtrack from there."
Unknown is whether the suspect is tied to another copper theft just across the street.
"From what I learned, like $2-to-3-million worth of copper," said Hernandez.