Attorneys for a Kansas man accused with plotting a suicide bombing at a Wichita airport are asking a judge to order the government to disclose whether mass surveillance first led authorities to the avionics technician.

The U.S. attorney’s office declined to comment Monday on the latest court filing in the case of Terry Loewen, an avionics technician facing terrorism-related charges. Loewen has been jailed since his December arrest for allegedly trying to bring a van filled with inert explosives onto the tarmac at Mid-Continent Airport.

His attorneys argued in a court filing Friday that prosecutors have given them no evidence indicating how Loewen first came to the attention of the FBI.

The dispute is important because the defense wants to suppress evidence obtained or derived from any unlawful electronic surveillance.