A 29-year-old Frederick man already convicted once of child sex crimes is facing a new federal indictment that could send him to prison for decades, after investigators say he used social media accounts to receive sexually explicit images of at least five minors. David Lee Mangum was indicted on new child sex abuse charges, according to the U.S. Attorney's Office, with prosecutors alleging the conduct took place in 2025 and 2026.
Mangum faces five counts of receiving child sexual abuse material and one count of possessing child sexual abuse material, as reported by WBFF. He also faces one count of transferring obscene material to a minor. According to the indictment, Mangum sent a video of himself engaging in sexually explicit conduct to one victim, and a search of his phone turned up several images of child sexual abuse material.
The case was investigated jointly by the U.S. Department of State's Diplomatic Security Service — Office of Investigations and the Frederick County Sheriff's Office, according to the U.S. Department of Justice. The involvement of a State Department security agency alongside a county sheriff's office typically signals digital forensics or cross-jurisdictional network tracing, and DSS is known to work alongside the DOJ's National Sex Offender Targeting Center and foreign law enforcement to trace online abuse networks that cross state or national lines.
A Prior Conviction and a Suspended Sentence
This is not Mangum's first brush with the justice system. He pleaded guilty in October 2021 in Frederick County to three felony counts related to filming, soliciting, and promoting child sexual abuse material, the report notes. He received a 10-year prison sentence, but all but 18 months of that sentence were suspended, officials reported.
That earlier, largely suspended state sentence stands in stark contrast to what he now faces under federal law. It remains unclear whether Mangum was still on probation or supervised release from that 2021 conviction when the new alleged conduct occurred, an open question that has not been addressed in available records.
Mandatory Minimums Could Mean Decades Behind Bars
Under federal law, the stakes have shifted dramatically. Mangum faces a mandatory minimum of 15 years and up to 40 years in prison for each of the five counts of receiving child sexual abuse material, and a mandatory minimum of 10 years and up to 20 years for the possession count. He also faces up to 10 years for transferring obscene material to a minor.
Federal law is built specifically to escalate penalties for repeat offenders in these cases. Under 18 U.S.C. § 2252A, statutory minimums jump sharply for defendants with prior sex offense convictions, according to FindLaw. That single prior conviction is why Mangum's case moved from a county courtroom with a suspended sentence to a federal indictment carrying the possibility of a life-altering prison term.
Why This Went Federal, Not State
The shift from local to federal jurisdiction traces back to the tools investigators say Mangum used. Federal child sexual abuse material statutes are triggered whenever offenses involve cell phones, internet platforms, or social media messaging, because that activity satisfies the federal interstate commerce requirement, per Eisner Gorin LLP. In other words, using a phone or an app to send or receive the material is often enough to move a case out of county court and into federal district court, where the penalties are far steeper.
Maryland's sex offender registry system adds another layer for anyone previously convicted. The state's three-tier classification system requires Tier I offenders to register for 15 years, Tier II offenders for 25 years, and Tier III offenders for life with quarterly in-person check-ins, according to JC Law. Failing to notify law enforcement of a new address, phone number, or vehicle within three days is itself treated as a separate criminal offense in Maryland, carrying up to three years in prison for a first violation.
Part of a Broader Federal Push
Mangum's indictment falls under Project Safe Childhood, a Department of Justice initiative established in 2006 to unify federal, state, and local agencies — including U.S. Attorneys' Offices and Internet Crimes Against Children task forces — in investigating online exploitation. The scale of the problem those task forces are working against is significant: the National Center for Missing & Exploited Children received 21.3 million CyberTipline reports of online child sexual exploitation in 2025 alone, escalating more than 53,000 urgent cases to law enforcement. Following the federal REPORT Act, the center also recorded a 158% jump in online enticement reports between 2024 and 2025 as tech platforms became required to report enticement alongside abuse material.
The Mangum case is one of several recent Maryland prosecutions Hoodline has tracked involving Project Safe Childhood, including a Houston man's guilty plea over exploiting eight Maryland teenagers through a CashApp scheme, and a separate case involving a former DC-area teacher who admitted to abusing a 16-year-old student. Whether additional victims or digital devices remain under investigation by the federal grand jury in Mangum's case has not been disclosed.
