A man from Sioux City, Iowa, has been sentenced to 10 years in federal prison for illegally building and firing two improvised explosive missiles. Daniel Graben, 60, received the sentence on December 5, 2024, following his guilty plea on July 18, 2024, to possession of a firearm by a felon.
The case stemmed from an incident on February 28, 2022, when a resident of rural Plymouth County reported seeing what appeared to be a "low flying mortar" over his house. The resident heard it explode in the distance and witnessed a second object that also exploded. Other witnesses reported hearing a "very large explosion," and an unexplained grass fire was discovered near the intersection of Plymouth County Roads C44 and K18. The Akron Fire Department extinguished the fire as law enforcement began their investigation.
Authorities found wreckage of two improvised explosive missiles linked to Graben and searched his home under a federal warrant. In his townhouse located in a populated area near a school, they discovered firearms, ammunition, military-grade explosives, bomb-making materials consistent with those found at the missile site, along with numerous other explosive devices.
Graben had prior convictions for arson and threatening crimes with intent to terrorize in California (2008) and possession with intent to deliver controlled substances in Idaho (2012).
United States District Court Judge Leonard T. Strand sentenced Graben in Sioux City to 120 months' imprisonment followed by three years of supervised release. He was also fined; there is no parole in the federal system.
This prosecution was part of Project Safe Neighborhoods (PSN), which aims to reduce violent crime through community collaboration and focusing on violent offenders while supporting prevention programs.
Graben remains in United States Marshal’s custody until transfer to federal prison.
The investigation involved multiple agencies including the Plymouth County Sheriff’s Office, Iowa State Fire Marshall Division, Sioux City Police Department, and ATF. Assistant United States Attorney Forde Fairchild prosecuted the case.