SAN DIEGO (AP) — Federal prosecutors on Tuesday dropped corruption charges against the longtime former head of the union representing Border Patrol agents, 18 months after accusing him of defrauding the organization out of hundreds of thousands of dollars.

U.S. District Judge William Hayes agreed to the government’s request to dismiss nine counts of conspiracy and fraud against Terence J. Bonner one day before a key hearing to determine what evidence would be allowed at trial. The decision followed a series of pretrial setbacks for prosecutors, including a ruling that that they cannot use pornographic images and other evidence seized from computers in Bonner’s home.