The woman found guilty of orchestrating the kidnapping and killing of her ex-boyfriend after he began fighting for visits with the daughter they shared has appealed her first-degree murder conviction.

Sheena Cuthill, 30, her husband Tim Rempel, 31, and his brother Wilhelm Rempel, 42, were convicted by a jury in April and each sentenced to life in prison with no chance of parole for 25 years.

In her notice of appeal, Cuthill makes three arguments in support of her application that her conviction should be overturned. She alleges:

The trial judge erred in denying Cuthill's application for exclusion of evidence on the basis of spousal privilege

The trial judge erred by charging the jury on the doctrine of willful blindness

The verdict was unreasonable

Normally communications between spouses are privileged but text messages between Cuthill and her husband were admitted as evidence even after her lawyer argued they shouldn't be.

The text messages between the two were some of the most damning evidence at trial.

"Can I trust Will to have this done without cops showing up on my doorstep?" Cuthill says to Tim Rempel in one text.

"I put a side of me away a long time ago that I told myself I would never let come back but this is OUR family and I will never let anyone ever tear … Sometimes things just need to happen," reads another of Cuthill's texts to her husband.

On the issue of willful blindness, Justice Alan Macleod told the jury that if they determined Cuthill set in motion the plan to harm Lane, then she was guilty of first-degree murder.

Court heard evidence that Lane, who was 24, was killed after he was kidnapped by the Rempel brothers from a parking lot in the city's northwest. His body was burned in a barrel at a gravel pit near Beiseker, Alta., 70 kilometres northeast of Calgary.

Lane's remains were discovered in the barrel along with his class ring and pieces of his cellphone four months after he disappeared.

Timothy Rempel has also appealed his conviction.

Wilhelm Rempel has not yet filed a notice of appeal.