California’s high-speed rail project lost a top leader this week without a replacement on tap, injecting fresh uncertainty into a project constantly in flux.

Joe Hedges, the project’s chief operating officer, left his job Monday, said rail spokesman Melissa Figueroa. She gave no details on his departure, saying the agency doesn’t discuss personnel matters. Hedges couldn’t be reached for comment.

His departure came the same day that rail board Chairman Tom Richards announced the conclusion of an investigation into personnel matters and allegations of fraud, though he said no fraud was found. The board formed a special committee in response to anonymous complaints about business practices and personnel, he said in brief remarks after the committee’s closed meeting ended. The committee began meeting in February, according to meeting notices.

The committee hired outside lawyers and a forensic accounting firm, Richards said. The board recommended communications and document processing changes to make sure the authority’s activities are accurately recorded, he said.

A state employee anonymously complained about Hedges’ business decisions in a December letter to the rail board, the Los Angeles Times reported.

Figueroa, the rail spokeswoman, declined to say if Hedges was the target of the investigation and whether his departure was related.

Hedges joined the project in 2018 under appointment from then-Gov. Jerry Brown. He came from the Washington State Department of Transportation, where he oversaw a $3 billion tunneling project in Seattle.

California’s rail project is far more ambitious and expensive. Voters in 2008 approved nearly $10 billion in bond money to build a high-speed rail line connecting Los Angeles and San Francisco to be up and running by 2020. In the years since, the project has been plagued by cost overruns and delays. Now officials hope to have trains running on a segment through the Central Valley by the end of this decade, more than 20 years after voters first backed the project.

Hedges was responsible for the project’s construction and engineering elements, including keeping them on schedule and within budget. He worked closely with Brian Kelly, the project’s chief executive officer, who also took that job in 2018. During their tenures, new Gov. Gavin Newsom shifted the project’s focus to the Central Valley and former President Donald Trump’s administration attempted to revoke federal funding. Costs kept climbing, and in February officials asked for yet another extension on part of the project.

Newsom has the power to appoint Hedges’ replacement. He was hired with a $337,000 salary, one of the highest in state government.

For now, Kelly will make “necessary personnel moves internally to ensure continued progress on construction in the Central Valley,” Figueroa said.