Sean Andrew Duncan, 22, of Sterling, Virginia, was sentenced today to 20 years in prison, to be followed by a lifetime of supervised release, for obstructing a counterterrorism investigation and receipt of child pornography.

Assistant Attorney General for National Security John C. Demers, U.S. Attorney G. Zachary Terwilliger for the Eastern District of Virginia, and Assistant Director in Charge Nancy McNamara of the FBI’s Washington Field Office, made the announcement after sentencing by U.S. District Judge Leonie M. Brinkema.

According to court documents, Duncan altered, destroyed, mutilated, concealed and covered up a thumb drive and memory chip with the intent to impede and obstruct an FBI terrorism investigation. He knowingly and unlawfully received images of minors engaged in sexually explicit conduct, and possessed thousands of such images including images of infants being sexually abused. In the statement of facts, Duncan admitted to his involvement with ISIS and production of child pornography.

Obstruction of Justice

In June 2017, the FBI learned that Duncan had been in contact with an individual who had been detained in a foreign country for actively planning to travel to join ISIS. In or around February 2015, Duncan told the individual that he wanted to make “hijrah” to Syria and that he wanted her to go with him. Later in February 2016, Duncan was denied entry into Turkey and returned to the United States.

Around this same time, the individual told Duncan she was upset at work due to non-Muslim women wearing shorts that exposed their bodies. Duncan replied with a link to a website, and a message saying she could “try this.” The link contained pictures and instructions on how to make weapons and bombs. The link was to an article titled, “How to build a bomb in the kitchen of your Mom” from Inspire magazine. In December 2016, Duncan contacted the individual and told her that he had come back from Turkey, where he and his wife were deported back to the United States. Duncan said he thought the FBI was monitoring him.

In or around October 2017, law enforcement authorities of a foreign government arrested one of their citizens (Recruiter 1) for inciting rebellion. Recruiter 1 is an ISIS recruiter who is suspected of drawing foreign fighters from around the world to Recruiter 1’s home country using social media. Recruiter 1 kept names and telephone numbers of individuals who had requested to join her social media and/or communication application groups. Recruiter 1’s notes included a handwritten name appearing to be “Sean Ibn Gary Duncan,” with Duncan’s known previous phone number and known previous mobile messaging account.

On or about Oct. 6, 2017, the Allegheny County Police Department (ACPD) provided a copy of Duncan’s phone to the FBI. ACPD had obtained this copy during an investigation surrounding the recent death of Duncan’s infant child (the cause of death in the autopsy was inconclusive). The FBI’s review of Duncan’s imaged phone revealed numerous internet searches for ISIS-related material, ISIS attacks, weapons, and body armor.

On Dec. 29, 2017, FBI agents executed a search warrant at Duncan’s residence. Upon execution of the warrant, the agents knocked on the door, identified themselves as FBI, and announced that they were there to execute a search warrant. Moments before the FBI agents entered the residence through the front door, Duncan ran out the back door, barefoot, and with something clenched in his fist. FBI agents guarding the back door yelled at Duncan to stop. Before stopping, Duncan threw a plastic baggie in the air and over the heads of the agents. FBI agents recovered the baggie thrown by Duncan. The baggie was a clear plastic bag, containing a memory chip from a thumb drive that had been snapped into pieces, and placed in a liquid substance that produced frothy white bubbles. Upon searching Duncan, agents recovered a broken casing for a thumb drive from Duncan’s pants pocket.

Receipt of Child Pornography

In December 2017, Duncan possessed a smartphone containing images of pre-pubescent minors that appeared to be engaged in sexually explicit conduct with adult males. Other images on the phone were of pre-pubescent minors posed to expose their genitalia in a sexual manner. Several of the images of child pornography were screen shots that Duncan had taken of websites containing child pornography that he had visited. The pre-pubescent minors in the photos were as young as infants, and the total number of images was in the thousands.

One image on his phone consisted of Duncan’s hand exposing the genitalia of an infant in a sexual manner. Also found on several of Duncan’s phones and electronic devices were thousands of videos and images of children and women that Duncan took in a voyeuristic manner. Several of the videos and images are taken in public venues such as stores, metros, parks and restaurants.

Assistant U.S. Attorneys Gordon D. Kromberg, Colleen E. Garcia and Jay V. Prabhu of the Eastern District of Virginia, and Trial Attorneys B. Celeste Corlett, Rachel Hertz and Troy Edwards of the National Security Division’s Counterterrorism Section prosecuted this case.