SIOUX CITY — A convicted Mason City child sex offender with a repeated history of violating Iowa’s sex offender registry laws has been sentenced to nine years in federal prison after authorities caught him illegally possessing ammunition during an investigation involving vulgar sexual messages allegedly sent to a minor girl.
Luke Braniff, 26, of Mason City, was sentenced in federal court in Sioux City to 108 months behind bars for being a felon in possession of ammunition.
Braniff (pictured at top) was previously convicted in Iowa of two counts of lascivious acts with a child in 2017. He was later convicted of sex offender registry violations in 2018, 2023 and 2025. Those felony convictions made it illegal for him to possess firearms or ammunition.
As NorthIowaToday.com previously reported, Braniff pleaded guilty on March 3, 2026, and admitted that he knowingly possessed ammunition despite understanding that his criminal record prohibited him from doing so.
Law enforcement officers discovered the ammunition while investigating reports that Braniff had allegedly sent vulgar sexual messages through Snapchat to an underage girl and requested nude images from the child.
The earlier federal case exposed the possibility that Braniff could face up to 15 years in prison. He remained in U.S. Marshals Service custody while awaiting sentencing.
U.S. District Court Judge Leonard T. Strand ultimately sentenced Braniff to nine years in federal prison, followed by three years of supervised release.
There is no parole in the federal prison system, meaning Braniff must serve the sentence under federal rules rather than receiving an early release through a traditional state parole board.
Braniff remains in the custody of the U.S. Marshals Service until he can be transported to a federal prison.
The Mason City Police Department investigated the case. Assistant U.S. Attorney Kraig R. Hamit prosecuted it.