QUEENSBURY (AP) – An upstate New York man who was sentenced to 23 years to life in the stabbing death of his estranged wife is seeking to have his guilty plea thrown out.

Clifford Burns was sentenced in September 2014 in the death of 42-year-old Patricia Burns, who was killed in a knife attack on Dec. 24, 2013, at her home in Lake Luzerne in Warren County.

The 48-year-old Schenectady man pleaded guilty to second-degree murder in April 2014, and then tried unsuccessfully to withdraw it.

The Post-Star of Glens Falls reports he filed a notice to dismiss the indictment against him before the sentencing. Burns filed a notice of appeal after sentencing, which was argued last week before an appeals court.

His attorney says that Burns’ guilty plea was a “clear case of coercion.”