A Buckfield man convicted of manslaughter in the 2020 death of his 2-month-old daughter has lost his appeal to the Maine Supreme Judicial Court.

Attorneys for 32-year-old Trevor Averill had argued that a new trial should be ordered or the sentence reconsidered due to what they deem numerous errors committed by the trial court.

In the appeal, Averill’s attorneys argued that the court should not have allowed video of rescue efforts to save the life of 2-month-old Harper Averill to be admitted as evidence at trial. They also argued that autopsy photos of the deceased girl likewise should have been omitted as evidence.

The court rejected both arguments on Thursday, stating that the photos themselves were not gruesome and that they conveyed relevant information to the jury.

As to video from cameras worn by first-responders, the court declared that the footage was not “unfairly prejudicial” and repeated that the footage had value for the jury.

In the judgment, the panel also found that the court did not err in admitting evidence of a rib fracture and skull fracture suffered by Harper Averill, pointing out that Trevor Averill’s attorney did not object to that evidence at trial.

The court further ruled that Averill’s sentence was proper and that evidence submitted at trial was sufficient to find him guilty of manslaughter.

In March of 2025, Averill was sentenced to 18 years in prison after being found guilty following two days of jury deliberations. He formally appealed the verdict and sentence in January.

According to trial testimony, Averill had taken the baby downstairs for feeding just after midnight on July 22, 2020. Minutes later, Averill hollered out to the child’s mother, who found Harper limp and unresponsive.

Medics brought the child by helicopter to Maine Medical Center in Portland, where she died four days later.

During the trial, which began in January 2025, state prosecutors said Harper Averill died of “non-accidental trauma,” which, according to expert witnesses, stemmed from a skull fracture and spinal hemorrhage caused by severe back and forth shaking.

Defense attorneys presented their own experts at trial; experts who suggested that Harper may have died from complications of injuries suffered when she was accidentally dropped weeks before her death.

Although Averill was ultimately convicted of manslaughter, the jury declined to convict him on a second charge of depraved indifference murder, for which he could have faced life in prison.