Shippensburg detective pleads guilty to possessing child porn

Matthew S. Pleisse, 36, of Shippensburg, pleaded guilty on Monday, Oct. 19, to possessing child pornography involving a prepubescent minor. The admission was announced by federal authorities on Thursday, Oct. 29, and confirmed details of a case that began with a search warrant in April 2025. Pleisse, who served as a detective with the Shippensburg Police Department, entered his plea before US District Judge Robert D. Mariani.

Federal investigators executed the search warrant at Pleisse’s home and seized several electronic devices, including a personal computer and a cell phone. Forensic examinations revealed that Pleisse used cryptocurrency to purchase child pornography from the dark web. Prosecutors stated that the material depicted prepubescent minors. The investigation was conducted by Homeland Security Investigations under the Department of Justice’s Project Safe Childhood initiative.

Assistant US Attorney Stephen W. Dukes described the financial trail during a May detention hearing. Dukes noted that Pleisse moved money from an M&T Bank account to Coinbase and through multiple cryptocurrency wallets. Dukes told the court that these steps were designed to conceal the evidence. “He’s intelligent,” Dukes said. “The means he used to obfuscate and to conceal his movements were technically sound.”

The conduct charged in the federal case began in July 2024. On July 7, 2024, Pleisse interviewed an 8-year-old girl who reported she had been raped. Pleisse documented the disclosure in a report at 11:45 a.m. and finished his shift at 3 p.m. He returned home to his wife and two children. Around 7:30 a.m. the next day, Pleisse began the series of transactions that prosecutors say constituted his first attempt to receive child sexual abuse material.

The federal indictment lists six attempted-receipt counts from July 2024 to October 2024. It also includes one count for receiving child pornography in January 2025 and one count for possessing it on a desktop computer in April 2025. Prosecutors said investigators found images of children and filenames referencing pedophilia on Pleisse’s devices. They also found he accessed websites advertising child sexual abuse material.

Pleisse’s role in the local police force draws attention to his prior work. In October 2022, he responded to a Sheetz at 529 East King Street in Shippensburg. A 14-year-old girl was found there in a state of heavy intoxication. The girl later reported that a 22-year-old employee had sexually assaulted her. Pleisse was among the first officers on the scene. Prosecutors noted that evidence suggests Pleisse had been accessing child sexual abuse material since 2023, a period overlapping with his duties on that investigation.

Under the plea agreement, Pleisse must resign from the Shippensburg Police Department within 10 days. He is also barred from seeking or accepting a position of public trust during his supervised release. Pleisse faces up to 20 years in federal prison, a fine, and a term of supervised release. Judge Mariani will impose the sentence after considering federal sentencing guidelines. No sentencing date has been announced.