The F.B.I. has arrested a Volkswagen executive in Florida, accusing him of playing a central role in a broad conspiracy to keep United States regulators from discovering that diesel vehicles made by the company were programmed to cheat on emissions tests.

The executive, Oliver Schmidt, a German who is the former top emissions compliance manager for Volkswagen in the United States, was arrested on Saturday by investigators in Florida on a charge of conspiracy to defraud the United States. He is expected to be arraigned on Monday.

The arrest of Mr. Schmidt is an escalation of the criminal investigation into emissions cheating by Volkswagen and comes amid talks between the company and the United States Justice Department about what penalties the carmaker should accept as part of a settlement.

After a study by West Virginia University first raised questions over Volkswagen’s diesel motors in early 2014, Mr. Schmidt played a central role in trying to convince regulators that excess emissions were caused by technical problems rather than by deliberate cheating, Ian Dinsmore, an F.B.I. agent, said in a sworn affidavit used as the basis for Mr. Schmidt’s arrest.