A pharmacy benefits management firm announced Tuesday that it is offering a $1 million reward for information leading to the conviction of whomever is threatening to divulge the personal information of millions of its members.

St. Louis-based Express Scripts disclosed last week it received an anonymous letter that included the names, Social Security numbers, birth dates and, in some cases, prescription information of 75 members. The writer or writers threatened to release millions more of similar records if the business failed to pay an unspecified sum of money.