A Butler County man who was arrested on terrorism charges has pleaded guilty to planning the kidnapping and execution of a U.S. military employee and an attack on a police station.

Prosecutors released previously sealed documents, including a plea agreement, on Thursday that detail the national-security case against Munir Abdulkader, 21, of West Chester.

The FBI Joint Terrorism Task Force arrested Abdulkader on May 21, 2015 after he purchased an AK-47, ending the task force’s two-year surveillance of him.

Unsealed court documents and the FBI gave this detailed account of Abdulkader’s case:

A native of Eritrea in east Africa, Abdulkader became a citizen of the United States in September 2006. He was a college student at a Xavier University in Cincinnati when he came onto the FBI’s radar after writing Twitter posts seen as sympathetic to Daesh fighters.

On a Twitter account that began in July 2014 and continued into 2015, Abdulkader posted a Daesh training video, lamented that his cousin had died fighting for Daesh and expressed his desire to travel and join the terrorist insurgency.

Abdulkader also stated his wish to attain martyrdom.

From March to mid-April 2015, Abdulkader began speaking with a confidential source about his intentions to travel to Syria and fight for the insurgency. He secured a passport, saved money for the trip and began making travel plans, but postponed the trip until May 2015 because of increased arrests of individuals traveling to join Daesh.