A sticky substance found at mail collection boxes outside La Jolla's main post office has triggered a federal investigation into a possible mail-theft scheme.

The substance was discovered at the blue USPS boxes outside the post office at 1140 Wall St. and reported on social media on Tuesday, Oct. 6, according to the La Jolla Light. Postal Inspector Patricia Mendoza of the U.S. Postal Inspection Service (USPIS) confirmed the investigation the following day.

Mendoza told the La Jolla Light the department is "actively investigating the recent incidents of glue or sticky substances involving the collection boxes."

It marks the third time a sticky substance has been reported on La Jolla mailboxes since August 2023.

A pattern across three years

In the first known incident, La Jolla resident George Fermanian found a clear adhesive on the inside lid of a USPS box on La Jolla Boulevard near Ravina Street. He described the tactic in the La Jolla Light's Aug. 29, 2023, report: "When you deposit your mail, the letter gets caught and does not drop into the main mailbox. A thief then easily retrieves the envelope and all contents."

That same month, sticky residue was reported at drive-up mailboxes outside the Postal Service's Rancho Bernardo Annex. Three boxes had sheets of paper taped over their chutes warning they were compromised, according to the same La Jolla Light report.

A second La Jolla incident followed in October 2024, this time on the outside of a mailbox at the same Wall Street post office. USPS strategic communications manager David Rupert said in the La Jolla Light's Oct. 28, 2024, report that the substance was believed to be "candy or gum or something else" and that there was no evidence mail had been stolen.

Federal penalties and what residents can do

Tampering with a USPS collection box is a federal crime. According to the USPIS, those convicted of destruction of federal property face up to three years in jail and fines up to $250,000.

No arrests have been made in connection with any of the three La Jolla incidents. The investigation remains active.

Mendoza recommended that residents who use collection boxes check the posted pickup times and avoid leaving mail in a box overnight or over the weekend. Residents can report suspicious activity near postal facilities to local law enforcement or the USPIS at (877) 876-2455 or online at postalinspectors.uspis.gov.