Police were investigating mosaic murals at two Marin elementary schools Friday after it was revealed that several murals by the same San Francisco artist contained hidden images with what authorities described as a “sexual connotation.”

The artist, Anthony Josef Norris, was arrested June 2 by the FBI after hundreds of pornographic images of children were discovered on his home computer.

Norris was the executive director of a nonprofit art education group, Kid Serve, which led dozens of children’s art installations at schools throughout the Bay Area, including at Bahia Vista Elementary School in San Rafael and Old Mill School in Mill Valley.

On June 15, San Francisco Unified School District officials notified police they had discovered hidden images embedded in mural tiles at Sunset Elementary School and three other schools.

Since then San Francisco police have inspected nearly 40 Kid Serve murals and removed approximately 100 small tiles that could potentially be inappropriate, San Francisco police Chief Greg Suhr said at a press conference Friday.

“These tiles are very small,” he said. “You would have to get close to these tiles to see the inappropriate images.”

Officials did not disclose details of the types of images found. Mike Biel, the department’s commander of investigations, said the confiscated tiles included both photograph negatives and drawn images that may be “construed as offensive.”

“As an adult,

you would look at these tiles and see some sort of sexual connotation to them,” he said.

On Friday, San Rafael police inspected a mural at Bahia Vista Elementary School in the Canal neighborhood but did not find anything deemed inappropriate, said San Rafael City Schools Superintendent Michael Watenpaugh.

“Based on my conversation with them (police), they indicated they weren’t able to identify anything at Bahia Vista that may be similar to what they found at other murals,” he said.

San Francisco police said authorities in San Rafael, Mill Valley and Oakland — also a Kid Serve site — had been notified of the hidden images, but it was not clear Friday if the Old Mill mural had been inspected. Mill Valley school and police officials could not be reached for comment Friday.

The large, colorful Bahia Vista and Old Mill murals were built by third- and fourth-graders in a combined effort dubbed the “Sister Project,” which was aimed at building ties between the two groups of students. The students at each school constructed parts of the other school’s mural; the murals contained images of plants and animals from the Mount Tamalpais watershed, a student reading a book and more. They were unveiled in 2008.

In addition to school projects, Norris has created murals for Starbucks, the Philadelphia Mural Arts Program, San Francisco Neighborhood Beautification Fund, the city of Oakland, MUNI and the San Francisco Department of Recreation and Parks, according to the Kid Serve website.

Contact Will Jason via email at wjason@marinij.com