Over a series of exchanges, the F.B.I. persuaded the sender to leave information at a dead drop in return for cryptocurrency payments. The F.B.I. then observed Mr. Toebbe and his wife, Diana Toebbe, at the location of the drop, in West Virginia.
With Ms. Toebbe acting as a lookout, Mr. Toebbe left an SD card concealed inside half a peanut butter sandwich in a plastic bag, according to the court documents. After the undercover agent retrieved the sandwich, Mr. Toebbe was sent $20,000.
Agents then set up another dead drop in Pennsylvania and a third in Virginia, where they said Mr. Toebbe deposited an SD card concealed in a package of chewing gum.
While working at the Bettis Atomic Power Laboratory, a little-known government research facility in West Mifflin, Pa., Mr. Toebbe would have had access to the documents that he is accused of passing to the undercover F.B.I. officer.
Many of the details of the exchanges were redacted in the court documents, but there was a reference to scaled drawings and maintenance details. One cited a note, which the documents suggest was written by one of the Toebbes, that the information “reflects decades of U.S. Navy ‘lessons learned’ that will help keep your sailors safe.”
The F.B.I. and the Naval Criminal Investigative Services arrested Jonathan and Diana Toebbe on Saturday. They will appear in federal court in Martinsburg, W.V., on Tuesday.