Federal prosecutors have quietly stepped into one of Oklahoma County's most closely watched cases, filing a new gun charge against Benjamin Plank, the man long tied to the 2022 ambush that killed a sheriff's deputy. The move comes on top of a yearslong fight in state court over Plank's mental competency, a battle that briefly wiped the murder case off the docket before prosecutors brought it back under a new law.
Federal Complaint Details Drug-User Gun Charge
In a criminal complaint and probable-cause affidavit filed in U.S. District Court, investigators say Plank admitted to long-term drug use and told them he had used methamphetamine on the morning of the August 2022 shooting. The filings also describe officers finding glass pipes that later tested positive for methamphetamine and marijuana, along with numerous rounds of ammunition in a backpack. Those findings form the backbone of a federal case accusing Plank, as an unlawful drug user, of possessing a firearm, according to KOCO.
How Investigators Say the Ambush Unfolded
Earlier investigative reports say Oklahoma County deputies went to serve an eviction notice at a southwest Oklahoma City home on Aug. 22, 2022, when they were met with gunfire. Sgt. Bobby Swartz was fatally wounded, and Deputy Mark Johns was critically injured. The shooter then allegedly sped away in a pickup truck towing a boat, before officers arrested a suspect outside a gate at Tinker Air Force Base, as reported by News 9.
Competency Fight and Refiled State Charges
The state case has been bogged down in a competency dispute for more than two years. In 2025, an Oklahoma judge found Plank incompetent to stand trial after doctors reported that his delusions and refusal to take medication were undermining efforts to restore him. That ruling led to dismissal of the criminal case and the start of civil-commitment proceedings, as detailed by NonDoc.
Prosecutors later brought the case back, refiling first-degree murder and shooting charges in January 2026 under new statutory authority that pauses the competency clock when a defendant refuses court-ordered medication, according to earlier KOCO reporting from January 2026.
What the Federal Count Means
The federal gun allegation appears to rely on 18 U.S.C. § 922, which makes it a felony under federal law for certain unlawful users of controlled substances to possess firearms. The statute and its wording are laid out in the federal code; the text of 18 U.S.C. § 922 is available through LII. Under long-standing doctrine, federal and state authorities can each pursue their own cases arising from the same conduct. The U.S. Supreme Court reaffirmed that so-called dual-sovereignty principle in its Gamble decision, with summaries of the ruling available on Oyez.
So far, there has been no public indication of how or when the new federal case might wrap up, and court filings beyond the complaint have not been widely circulated. Federal matters typically move on their own track, with initial appearances, possible detention hearings and discovery running alongside whatever is happening at the county courthouse. That means the coming weeks could feature parallel filings in both Oklahoma County court and federal court as lawyers and judges sort out the next steps.
