A 38-year-old man from New Hampshire is set to spend decades behind bars for the murder of his former girlfriend, an incident that occurred while their 4-year-old daughter was nearby.

Dustin Mark Duren was sentenced last week to between 45 years and life behind bars for killing 31-year-old Caitlyn Naffziger. A jury in October convicted him of second-degree murder, reckless conduct with a deadly weapon and endangering the welfare of a child.

Prosecutors revealed that the couple, Duren and Naffziger, were embroiled in a contentious custody battle over their two young children, aged 4 and 1 at the time. In January 2024, Duren relocated from Minnesota to New Hampshire, taking one child with him. Naffziger followed shortly after, flying from Minnesota to New Hampshire with the other child on February 27, 2024.

All four were at Duren’s apartment in Berlin, where tensions flared as he repeatedly asked Naffziger when she planned to leave, making it clear he did not want her there.

“She either ignored his requests or failed to satisfy his demands,” prosecutors noted in Duren’s sentencing memorandum. “This led to his frustration mounting into anger.”

On February 29, 2024, Duren attempted to force Naffziger out of his apartment, insisting that the children remain behind. Naffziger refused to comply. As she sat on the couch with their 4-year-old, wrapped in a pink unicorn blanket, Duren violently pulled the child away and shot Naffziger in the head. His expertise as a former Marine marksman left no doubt about his lethal intent, prosecutors asserted.

Later, the girl told a doctor that the gunshot hurt her ears.

“Mommy and daddy were fighting,” she told the doctor. “Daddy hurt me and mommy. Mommy had lots of blood.”

After shooting the victim, Duren grabbed the kids and took off, which sparked an Amber Alert. Witnesses said they saw Duren and the kids in the parking lot of an Applebee’s. The children were unharmed.

Duren testified during the trial, claiming he felt as if his ex was going to kidnap the children. But the jury didn’t buy his argument and convicted him after deliberating for roughly five hours.

At Duren’s sentencing hearing, Naffziger’s aunt Shannon Spurgeon spoke about the impact the murder has had on her loved ones.

“Nothing can prepare you for the heartbreak of losing someone like Caitlin,” Spurgeon said. “Losing her in such a violent and senseless way shattered everyone who loves her.”

The victim’s stepfather Tim Smith said the murder “culminated years of classic textbook domestic violence” such as isolating her from her family and controlling her.

“When the control that Dustin imposed on Caitlyn, which was facilitated by using their children as pawns, was lost, he knew he had lost control, because Caitlyn told him so,” Smith said. “Like so many abusers, Dustin resorted to murder in a vicious attempt to maintain that control at all cost.”