HSI, law enforcement partner investigation results in repeat offender sentenced to 10 years in prison for possession of images of child rape and abuse

SEATTLE, Wash. — A 68-year old SeaTac, Wash. man was sentenced today in U.S. District Court to 10 years in prison and 15 years of supervised release for possession of images of child rape and abuse, announced Special Agent in Charge Robert Hammer, who oversees Homeland Security Investigations (HSI) operations in the Pacific Northwest and Tessa M. Gorman, Acting U.S. Attorney for the Western District of Washington.

Michael David Mathisen, who pleaded guilty in October 2020, has past convictions in 1984 and 1994 for sexually molesting children under the age of nine. At today’s sentencing hearing, Judge Richard A. Jones noted that people such as Mathisen create the market for child pornography, and that the creation of the images damages the most vulnerable among us. “These young victims do a life sentence,” Judge Jones said.

Mathisen was contacted by law enforcement in October 2019, following a referral from Microsoft to the National Center for Missing and Exploited Children (NCMEC) that the account, later linked to Mathisen, was uploading images and searching on the internet for images of children engaged in sexually explicit conduct. HSI and the King County Sheriff’s Office obtained Mathisen’s electronic devices. A search of the electronic devices revealed 19 files with images of children being sexually molested and abused.

The case was brought as part of Project Safe Childhood, a nationwide initiative to combat the growing epidemic of child sexual exploitation and abuse launched in May 2006, by the Department of Justice. Led by United States Attorneys’ Offices and the Criminal Division's Child Exploitation and Obscenity Section (CEOS), Project Safe Childhood marshals federal, state and local resources to better locate, apprehend and prosecute individuals who exploit children via the Internet, as well as to identify and rescue victims.

The Internet Crimes against Children Task Force led by the Seattle Police Department coordinated the investigation. HSI and the King County Sheriff’s Office completed the Mathisen investigation.

HSI is a directorate of U.S. Immigration and Customs Enforcement (ICE) and the principal investigative arm of the U.S. Department of Homeland Security (DHS), responsible for investigating transnational crime and threats, specifically those criminal organizations that exploit the global infrastructure through which international trade, travel and finance move. HSI’s workforce of over 10,400 employees consists of more than 7,100 Special Agents assigned to 220 cities throughout the United States, and 80 overseas locations in 53 countries. HSI’s international presence represents DHS’s largest investigative law enforcement presence abroad and one of the largest international footprints in U.S. law enforcement.