On Friday, officials from the California Department of Public Health (CDPH) removed radioactive material from a San Carlos home formerly owned by recently deceased SLAC National Accelerator Laboratory employee Ronald Seefred.

CDPH officials arrived at the house on the 1000 block of Cedar Street around 10:30 a.m. and had completed the removal process by 3:30 p.m. when the San Mateo County Sheriff’s Office issued an alert to the public.

“The hazardous material has been removed to a secure State facility outside of the County,” the alert read.

The CDPH removal on Friday was a response to a Thursday report from the San Mateo County Environmental Health Services division to the Redwood City Fire Department that alerted the city to radioactive materials found in the unoccupied home.

The substances were discovered in a backyard shed during a fire department sweep of the house and property and were later identified by Redwood City Fire Chief Stan Maupin as cobalt-57 and radium-286.

Maupin told The Mercury News that he and his firefighters were “100-percent confident” that the radioactive elements were contained within the shed and that the material posed no danger to the community.

Maupin also told the San Francisco Chronicle that he suspected no “nefarious or bad intent” concerning the material.

The house has remained unoccupied since Seefred’s death in January. Seefred worked at SLAC, a Menlo Park lab jointly run by the U.S. Department of Energy and Stanford University, from 1961 until his retirement in 2003.

Brian Sherin, the lab’s deputy director of operations could not confirm whether the involved substances were used during Seefred’s employment.

“To our knowledge, none of the materials described came from SLAC,” Sherin said to the San Francisco Chronicle. “We have a very detailed accounting system and all of our materials are accounted for.”

The Daily has reached out to SLAC for comment.

Contact Andrew Tan at tandrew ‘at’ stanford.edu.