An Iowa WHITE #CriminalJustice #man who strangled his ex-girlfriend until she passed out and then executed her parents in a chilling ambush will spend the rest of his life behind bars, a judge ruled Friday.
Luke R. Devening, 26, of Pleasant Hill, was sentenced to three consecutive life terms without parole for the March 2024 murders of Dennis Mahon, 65, and Christine Mahon, 63, and the attempted murder of his former girlfriend, identified as A.M. in documents.
The brutal attack unfolded on the night of March 11, 2024, when Devening forced his way into the Mahons’ rural home near Runnells. Armed with a 9mm, he first choked A.M. unconscious in an upstairs bedroom, then waited for her parents to return from a dinner outing.
When Dennis and Christine Mahon walked through the door, Devening shot each of them multiple times at point-blank range in front of their semiconscious daughter, prosecutors said. He fled the scene but was arrested hours later after a statewide manhunt.
A.M. survived and testified against Devening during his October trial, recounting how he had stalked and threatened her in the weeks leading up to the murders.
“He told me that night, ‘If I can’t have you, no one will,’” she told the court through tears. “Then he killed my parents right in front of me.”
Jurors took less than two hours to convict Devening on two counts of first-degree murder and one count of attempted murder.
At Friday’s sentencing, Dennis Mahon’s brother, Michael, addressed the court: “Luke Devening didn’t just kill two people that night — he destroyed an entire family. There is no punishment severe enough.”
Devening is expected to be transferred to the Iowa State Penitentiary at Fort Madison in the coming weeks. His conviction is automatically appealed under Iowa law, but legal experts say the mandatory life sentences are virtually certain to be upheld.
