SANTEE, Calif.—A woman suspected of trying to sneak methamphetamine to an inmate in a San Diego-area jail via a drug-soaked piece of mail was behind bars herself on Sept. 11.

Misty S. Vantine, 45, was arrested on Sept. 8 in a parking area at George Bailey Detention Facility in Otay Mesa. according to the San Diego County Sheriff’s Department.

Deputies staffing a jail mail-processing facility on Aug. 23 noticed that a letter intended for an inmate appeared to have been drenched in some type of liquid and dried, Sgt. Aaron Brooke said. Running a chemical test on the piece of correspondence, they discovered that it had been infused with liquid methamphetamine.

Investigators ultimately determined that Ms. Vantine allegedly had sent the drug-spiked letter, Mr. Brooke said.

Ms. Vantine was booked into Las Colinas women’s jail in Santee on suspicion of sending an illicit drug to a jail facility, trying to sell a controlled substance to an inmate and criminal conspiracy.