The surprising decision by federal prosecutors in San Francisco to drop pursuit of a potential $562 million fine against one of the nation’s largest utilities after a deadly pipeline blast marked the second time in recent months that the office has backed down in a high-profile criminal case against a major corporation.

The move Tuesday involving Pacific Gas & Electric Co. came weeks after the U.S. attorney’s office abruptly abandoned drug trafficking allegations against shipping giant FedEx.

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California regulators previously fined the utility $1.6 billion. Robert Weisberg, a criminal law professor at Stanford University, said it’s possible prosecutors felt jurors might see the federal penalty as piling on and be upset at having to spend substantially more time hearing testimony. That could lead them to side with the utility.