A northern Virginia man charged with joining what he thought was an al-Qaida plot to bomb the Washington region’s Metrorail system is expected to enter a guilty plea in federal court.

Farooque Ahmed of Ashburn is a naturalized citizen from Pakistan.

He is scheduled to appear Monday at U.S. District Court in Alexandria for a change of plea hearing.

The exact charges to which Ahmed will plead are unclear. He was initially charged with conspiring to provide material support to al-Qaida and collecting information for a terrorist attack on a transit facility.

Authorities say Ahmed plotted with people who turned out to be part of a six-month government sting. He allegedly took video of northern Virginia subway stations and made suggestions to inflict the highest number of casualties.