Delaware State Police say Jose Oyola, 47, of Greenwood, targeted 20 members of the Hispanic community between January 2004 and March 2011.
Police say Oyola charged the victims hundreds, sometimes thousands of dollars to complete their tax returns before they entered the English as a Second Language (ESL) program at Sussex Tech Adult Education.
In some cases, police say, Oyola also promised to help the victims obtain work visas, driver's licenses and secure housing through Habitat from Humanity.
Authorities say Oyola took the victims' money and never provided the services promised. In one case, police say Oyola threatened one victim by saying he would approach immigration officials with personal information about the victim if the victim ever returned to the ESL program.
Oyola was arrested Thursday and charged with multiple counts of theft and extortion.
He was released on $22,500 unsecured bond.
Delaware State Police are asking anyone who believes they were victimized by Jose Oyola to contact Master Corporal George Camacho at 302-856-5850 ext. 324 or by using the Delaware State Police Mobile Crime Tip Application available for download at: http://www.delaware.gov/apps/.
Information may also be provided by calling Delaware Crime Stoppers at 1-800-TIP-3333, via the internet at www.tipsubmit.com, or by sending an anonymous tip by text to 274637 (CRIMES) using the keyword "DSP."