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Department of Justice

U.S. Attorney's Office
District of Idaho
Joshua D. Hurwit, United States Attorney
Contact: Cassie Fulghum
For Immediate Release
Wednesday, April 24, 2024

Twin Falls Man Sentenced to Federal Prison for Providing Illegal Firearms, Including 'Glock Switches,' to Californian With Cartel Ties

First Prosecution in Idaho for an Offense Involving Illegal “Glock Switches”

BOISE – Arthur Michael Rhyne, a/k/a Arthur Michael O’Neil, 41, of Twin Falls, was sentenced to 7 years in federal prison for unlawful possession of firearms, U.S. Attorney Josh Hurwit announced today.

According to court records, in August 2023, special agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) began investigating Rhyne for illegally obtaining and shipping firearms.  Agents learned that Rhyne attempted to ship a loaded Glock 9mm pistol with a machinegun conversion device, called a “switch,” installed on the Glock.  A machinegun conversion device is a device that, when integrated with a semiautomatic firearm, will convert it to fire in fully automatic capacity.  This conversion of a Glock pistol with a “switch” machinegun conversion device, for example, will result in a rate-of-fire of approximately 1,100 – 1,200 rounds per minute, making these devices particularly lethal.

Glock 9mm pistol with “switch” machinegun conversion device installed

Glock 9mm pistol with “switch” machinegun conversion device installed that Rhyne attempted to ship in the mail.  (Photographs obtained from the publicly filed Government’s Sentencing Memorandum, ECF No. 55.)

In October 2023, ATF agents obtained a federal search warrant for Rhyne’s residence in Twin Falls.  Upon searching a safe in the residence, agents located 16 firearms, 14 machinegun conversion devices, 3 high-capacity drum magazines, 3 suppressors, more than 2,100 rounds of ammunition, including armor piercing ammunition, and 78 grams of methamphetamine.  In addition to the Glock “switches,” agents also seized “Drop In Auto Sears,” which are machinegun conversion devices designed for a rifle platform firearm.

“Drop In Auto Sears” machinegun conversion devices

“Drop In Auto Sears” machinegun conversion devices also located in Rhyne’s safe.  (Photograph obtained from the publicly filed Government’s Sentencing Memorandum, ECF No. 55.)

At the time of his arrest, Rhyne was prohibited from possessing firearms due to a 2008 California conviction for second degree commercial burglary. 

According to court filings, Rhyne told agents that he was transferring firearms and ammunition to individuals in California.  Rhyne admitted that he was purchasing the items, including Glock switches and silencers from a person overseas and then sending firearms and Glock switches to California.  He also discussed armor piercing ammunition located in the safe and said it was purchased for his contact in California. When describing his contact in California who was receiving the firearms, Rhyne described him being a cartel drug dealer and said he believed the guns were going to Mexico.   

“Glock switches and similar conversion devices are simple to manufacture and are easy to install.  They turn regular firearms into machineguns capable of inflicting a tremendous toll in a few split seconds,” said U.S. Attorney Hurwit.  “We will not tolerate the proliferation of the devices on our streets and will use all of our resources to hold accountable anyone who would distribute these deadly and illegal devices.”

“Mr. Rhyne clearly knew he was prohibited from possessing, let alone transferring, machine guns and other firearms and ammunition,” said ATF Seattle Field Division Special Agent in Charge Jonathan Blais.  “So, this sentence is well warranted.  ATF will continue to investigate those prohibited from possessing firearms and still continue to do so, as well as those who possess these deadly machinegun conversion devices.”

“Today's sentencing marks a significant victory in our ongoing efforts to combat illegal trafficking of these “trigger switches”.  By partnering with the ATF, we have demonstrated our unwavering commitment to the goal of safe and secure communities for all,” said Inspector in Charge, Anthony Galetti, of the U.S. Postal Inspection Service.  “The use and distribution through the mail of these illegal conversion devices poses a serious threat to public safety, and we will continue to work tirelessly to dismantle such operations.”

When sentencing Rhyne, Senior U.S. District Judge B. Lynn Winmill noted the case was “spine chilling.”  Judge Winmill stated that by arming people with automatic firearms, silencers, and high-capacity magazines, Rhyne had created a law enforcement officer’s worst nightmare.  Judge Winmill also ordered Rhyne to serve three years of supervised release following his prison sentence and to forfeit all recovered firearms and ammunition.  Rhyne pleaded guilty to the federal charge in December 2023.

U.S. Attorney Hurwit commended the work of the ATF, the U.S. Postal Inspection Service, and the Twin Falls Police Department, for their collaborative work on this case.

This case was prosecuted by Assistant U.S. Attorneys Erin Blackadar and Christopher Atwood.

This case is part of Project Safe Neighborhoods (PSN), a program bringing together all levels of law enforcement and the communities they serve to reduce violent crime and gun violence, and to make our neighborhoods safer for everyone.  On May 26, 2021, the department launched a violent crime reduction strategy strengthening PSN based on these core principles: fostering trust and legitimacy in our communities, supporting community-based organizations that help prevent violence from occurring in the first place, setting focused and strategic enforcement priorities, and measuring the results.


RhyneA_Government's Sentencing Memo

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