A former assistant prosecutor is puzzled why Gov. Chris Christie commuted the 40-year sentence of a convicted murderer days before the Republican left office.

Christie on Friday issued an order that led to the release of 50-year-old Lisa Pyatt from prison on Saturday. She was sentenced to serve at least 30 years in prison in 1993 for stabbing her fiance in the heart three days before their wedding in 1991.

Pyatt's lawyer used a battered woman's syndrome defense.

Former assistant Ocean County prosecutor William Cunningham tells the Asbury Park Press he proved Pyatt was not a victim and had accused a previous boyfriend of domestic violence.

Christie's order did not explain why he commuted the sentence. It said Pyatt had applied and the state Parole Board had investigated.