Missouri ? Two pipe bombs mailed to companies in Chicago and Kansas City, Mo., appear to be linked to a suspect who has been sending increasingly threatening letters to financial institutions since at least 2005, a corporate counterterrorism expert said Saturday.

The devices arrived a day apart. Officials have suggested in both cases that the devices were not working bombs that could have exploded.

But the bombs appear to be a sign that the suspect, who calls himself the “The Bishop,” is “upping the ante,” Fred Burton, vice president of counterterrorism for Stratfor, an Austin, Texas-based security and intelligence firm, wrote in a report Wednesday.

FBI spokesman Jeff Lanza declined Saturday to comment on Burton’s report and said the case is an ongoing investigation involving multiple FBI field offices and the U.S. Postal Inspection Service.