53-year-old James Thomas of Newark, Del. was arrested at his home Monday.
The bomb threat came in at 12:14 p.m. on Thursday March 7th and forced the evacuation of the courthouse for more than two hours.
Thomas is charged with Terroristic Threatening, a Class F Felony, and was being held on $3,000 cash bond.
Prosecutors have not said what prompted Thomas to make the threat.