A spokesman for the Martinez Refining Company confirmed Saturday that the U.S. Department of Justice is investigating a November release at the refinery.

"We are aware of the Department of Justice's investigation and as a matter of policy do not comment on pending legal matters. We are cooperating with all relevant agencies, including with respect to any ongoing investigations related to the incident," Brandon Matson said in an emailed statement.

"We would, however, like to take this opportunity to once again apologize to the Martinez community for the spent catalyst release on Nov. 24, 2022. We have thoroughly investigated the incident to identify appropriate corrective actions and we are committed to implementing them," Matson said.

The release of "spent-catalyst" started around 9:30 p.m. Nov. 24 and continued into the early hours of Nov. 25, showering the surrounding community in the dust-like substance. Samples of the dust later showed elevated levels of aluminum, barium, chromium, nickel, vanadium, and zinc, all of which could cause respiratory problems.

Contra Costa County policy required MRC to alert the community via the county emergency system and to immediately notify the health department, neither of which happened. County health officials say they learned about the release via media reports a day and a half later.