A Detroit who was arrested after buying explosives from an undercover agent is facing multiple federal charges.

According to an indictment unsealed in federal court, Sebastian Gregerson, aka Abdurraahman Bin Mikaayl, 29, is charged with receipt of explosive materials with intent to harm, two counts of unregistered possession of a destructive device and unlicensed receipt of explosive materials.

According to the indictment, Gregerson received the explosives, which contained 26 ounces of Composition B, a combination of TNT and RDX, "with knowledge and intent that said explosive materials would be used to kill, injure, and intimidate a person."

The complaint chronicles a counterterrorism investigation that began in April 2015 following a tip that Gregerson, who the FBI said also is known as Abdurrahman bin Mikaayl, had weapons. The FBI said he bought grenades on Sunday from the undercover agent in Monroe and was arrested.

The complaint said Gregerson earlier purchased "an arsenal of weapons, ammunition, tactical gear and tactical training materials." It doesn't say whether Gregerson was planning an attack or why he was purchasing explosives. The U.S. attorney's office in Detroit hasn't elaborated.

In June, the FBI said Gregerson bought road spikes online that can be used to slow or disable vehicles. Other purchases included tactical training items, including handguns and dummy rounds.

"The purchase of training versions of these weapons makes it unlikely that the weapons were purchased for recreational use, such as hunting," the complaint states.

Read the indictment, followed by the original complaint, below.

Gregerson Superseding Indictment by WXYZ-TV Channel 7 Detroit on Scribd

Criminal Complaint by WXYZ-TV Channel 7 Detroit on Scribd