The U.S. Postal Inspection Service posted a $100,000 reward late Wednesday for information about a flurry of threatening letters sent to JP Morgan Chase facilities, its CEO Jamie Dimon, and several federal banking offices around the country this week.
"You need to be pay back. You will be killed in 10 days," one of the typewritten letters read, federal law enforcement officials told ABC News.
Another letter, addressed to the JP Morgan Chase CEO, Jamie Dimon, in New York, threatened a series of attacks ending in an Oklahoma City-like bombing. The writer accused Dimon of stealing Washington Mutual, which JP Morgan Chase recently took over.
At least 45 letters, all postmarked in Amarillo, Texas on October 17 and 18, were sent to the Chase bank offices, the FDIC office in Dallas, the Office of Thrift Supervision in Dallas, and the Federal Home Loan Bank in Atlanta, federal law enforcement officials said.
The letters contained a powdery substance which tests have shown to be harmless.
Authorities say the letters "articulated threat of bodily harm" and appeared to be connected to lending practices of the bank.
Click here to see photographs of the letters on the FBI's website.
Postal inspectors said the public should "take no action to apprehend this person yourself."
Inspectors said anyone with information should contact authorities at 1-877-876-2455.
In a separate case, the FBI said its field office in San Diego has opened an investigation into a series of letters sent to the Los Angeles Times and the campaign offices of Senator Barack Obama in New York, Philadelphia and Los Angeles.
Those letters also contained substances, including sand and food seasoning. One letter said "the world will end" if Obama was elected, officials said.