The envelope of a letter sent to a retailer this summer, containing allegations about Hampton Creek's products. The return address names Josh Tetrick, Hampton Creek's CEO; the company says he did not write this letter.

An investigator hired by Hampton Creek, the Silicon Valley food startup famous for its eggless mayonnaise, says a mysterious entity appears to be trying to sabotage it.

An unsigned letter sent this summer to an unnamed major retailer claimed that Hampton Creek had contaminated and mislabeled products, according to the investigator. And the return address indicated that it was from CEO Josh Tetrick — even though Hampton Creek denies he wrote it.

The investigator told BuzzFeed News that this was one of two known anonymous letters — and that the other was sent to Target, which issued a high-profile removal of Hampton Creek’s products as a result.

While it’s unclear whether the two letters were identical or sent by the same person, the identity of the sender or senders is “the million-dollar question,” said the investigator, who requested anonymity. “It’s clearly fraud.” He also said that Hampton Creek is “weighing their legal options.”

At the time it pulled the items in late June, Target publicly said that the allegations it had received were unconfirmed, but specific and serious enough to warrant action.

The claims included allegations that pathogens like salmonella and listeria were found in Hampton Creek products and at one of the facilities where the company’s products are made, that some products were incorrectly labeled as non-genetically modified, and that the company failed to list honey as an ingredient in its sweet mustard salad dressing.

