Authorities said the group is responsible for some of the city's most notorious acts of vandalism, most notably L.A.'s largest tag: the giant, half-mile-long "MTA" scrawl that appeared last year along the concrete banks of the Los Angeles River near downtown.
But on Wednesday, authorities said they finally had arrested the MTA crew, including "Smear," a well-known "graffiti artist" whose work has been sold in some downtown L.A. art galleries.
These are not kids from the streets.
Los Angeles County sheriff's officials said one of the suspects drives a $60,000 BMW while another wore a diamond-and-ruby-encrusted Metro logo pendant valued at $27,000.
"These individuals are responsible for tags not only in Los Angeles, but Las Vegas and San Francisco," said sheriff's Cmdr. Dan Finkelstein, chief of the Metropolitan Transportation Authority police.
Authorities have long been frustrated by MTA, which they said is responsible for thousands of tags on businesses and public spaces, as well as transit buses and trains, which has been the taggers' particular target.
The crew allegedly also defaced freeway overpasses and signs as motorists whizzed by below them.
During raids Wednesday morning, Finkelstein said, investigators found customized, high-pressure fire extinguishers that, when filled with paint, allow taggers to shoot paint on the underside of a freeway overpass and produce tags.
But officials said the taggers outdid themselves when they hit the concrete banks of the Los Angeles River in downtown's industrial district.
Authorities estimate that it took about 400 gallons of paint -- 300 gallons of white and 100 gallons of black -- to create three block letters that cover a three-story-high wall and run the length of several blocks between the 4th Street and 1st Street bridges.
The tag has been an eyesore visible from downtown high-rises and freeways for months. But removing it is proving difficult -- and costly.
The Army Corps of Engineers estimates that removing the MTA tag from the river alone will cost $3.7 million because hazardous materials crews must create an elaborate dam to capture all the paint and runoff water so it doesn't get into the riverbed.
On Wednesday, deputies arrested Smear, whose real name is Cristian Gheorghiu, 32, at his home in the east Hollywood area, said sheriff's Sgt. Augie Pando.
Authorities also arrested Shaun Alexander, 27; Sergio Ayala, 25; Eduin Miramontes, 23; Nicholas Rem, 28; Juan Rocha, 22; and Ryan Swenson, 27, at their homes in the Los Angeles area.
Roger Gastman, author of several graffiti books who is working on a history of graffiti, said MTA -- also known as Melting Toys Away and Must Take All -- has been generating buzz in the graffiti art world for several years.
Smear in particular was able to sell "street art" to collectors.
"There is so much demand for street art right now," Gastman said.
He said the L.A. River tag is the taggers' calling card.
"It is definitely a statement," Gastman said. "To do something that big and bold it takes organization. . . . They were working on a slant and they got all the proportions right."