PORTLAND – The owner of a Saco accounting and payroll firm that’s under investigation for mismanagement of its clients’ money has been arrested in Florida, federal prosecutors said Thursday.

John Baert, owner of Harmon-Baert Associates, was arrested by U.S. Postal Service inspectors and Internal Revenue Service agents Thursday morning at a relative’s home in Parrish, Fla., said Toby Dilworth of the U.S. Attorney’s Office.

Baert was charged with three criminal counts of mail fraud, Dilworth said. Baert was scheduled to make his first court appearance Thursday afternoon in Tampa. Dilworth said charges against Baert could be elevated if he is indicted.

Harmon-Baert Associates did payroll processing and accounting, including paying taxes, for about 400 businesses for 20 years until it abruptly closed Nov. 20. Federal agents raided the business and Baert’s home Nov. 25 and confiscated files and documents from both.