A Sabattus man sent to prison for 55 years after he was convicted of killing his ex-girlfriend is making a second bid for a new trial. Daniel Roberts is asking Maine’s highest court to vacate his 2007 conviction. The 44-year-old Roberts was found guilty of the August 2005 shooting of 29-year-old Melissa Mendoza. The couple was involved in a custody dispute over their then 2-year-old daughter. Roberts said at the trial the shooting was self-defense. The Sun Journal, reports that Roberts alleges in his appeal that, among other things, he was denied his due process rights, his right to a public trial and that his defense lawyer was ineffective His previous appeal was denied in 2011.