PORTLAND - Nearly a year after Daniel Roberts was sentenced to prison for shooting his ex-girlfriend, the Sabattus man will try to get a new trial.

Roberts and his lawyer are expected to be in the Maine Supreme Judicial Court Thursday afternoon in an attempt to have the murder conviction overturned.

Roberts was sentenced last June to 55 years in prison for the 2005 killing of Melissa Mendoza, 29. He was convicted of the charge in February 2007.

On Aug. 15, 2005, Roberts shot Mendoza in the back of the head at his home in Sabattus. He never denied shooting his ex-girlfriend, the mother of their then 2-year-old daughter, but said he did so because he believed Mendoza was going to harm their daughter.

The jury did not accept the argument and found Roberts guilty of murder.

The appeal mostly argues that errors were made in the instructions given by the judge presiding over the case to the jury at the end of prosecution and defense arguments.

The appeal contends that:

• the court abused its discretion in admitting photographs of Mendoza and her daughter over the defendant's objections;

• the court abused its discretion in excluding the testimony of two women who would have supported the claim that Mendoza had threatened to kill Roberts;

• the admission of Mendoza's protection-from-abuse affidavit violated Roberts' constitutional rights;

• the court abused its discretion in admitting evidence of past incidents of vandalism to vehicles owned by Mendoza and another woman;

• the court erred in instructions to the jury on justification;

• the court erred in instructions to the jury on the elements of criminal restraint by a parent;

• the court erred in instructions to the jury on ignorance of law or fact;

• the court erred in instructing the jury that the state needed to prove that Roberts did not believe Mendoza was about to use deadly force and commit kidnapping when she was shot;

• the court erred in instructing the jury on the provocation element of justification;

• the prosecution's closing argument constituted prosecutorial misconduct.

Roberts' lawyer, Tom Marjerison, will argue the appeal at 1 p.m.