FREDERICTON -- A man found guilty of first-degree murder in the 2009 death of his 16-year-old cousin has had the appeal of his conviction dismissed by the New Brunswick Court of Appeal.

Curtis Bonnell asked the court to overturn the conviction and order a new trial after he was sentenced to life in prison with no parole eligibility for 25 years in the death of Hilary Bonnell.

Defence lawyer Peter Corey argued last April that the trial judge in his instructions to the jury should have related the evidence they heard to a possible finding of manslaughter.

Corey also said the trial judge erred by allowing text messages Hilary Bonnell sent before she died to be entered as evidence.

The jury was shown two text messages that she sent to Haylie Bonnell, the accused's sister, on the morning she disappeared. They read, "Please answer me I'm scared," and "OMF text me I'm scared."

Corey argued there was nothing in the messages to identify who she was with or what scared her.

In a written decision released Thursday, the court dismissed the argument.

"It is clear in the instructions to the jury that the text messages were introduced to illustrate Hilary Bonnell's state of mind. It is within that context that the trial judge instructed the jury to consider the text messages. There was no error," wrote Justice Kathleen Quigg, adding that the instructions to the jury "were more than adequate."

The two other judges on the panel concurred.

During the trial, the Crown alleged Bonnell picked up his cousin on a rural stretch of road near the Esgenoopetitj First Nation on Sept. 5, 2009, sexually assaulted her and killed her. He was arrested on Nov. 8, 2009, and the next day led police to a remote site where the girl's body had been buried.

Police interviews entered as evidence show Bonnell saying that he had sex with Hilary, fought with her, and killed her by holding his hand over her mouth to stop her from screaming.

But he offered a different version of events at his trial, testifying that he woke up after a night of alcohol and drugs to find Hilary dead next to him in his pickup truck. He said he panicked and buried her in a remote wooded area.