PORTLAND — The state’s highest court on Thursday denied a Sabattus man a new trial in the fatal shooting death of his ex-girlfriend and mother of their 2-year-old daughter.

Daniel Roberts, 45, claimed that his constitutional rights had been violated during his 2007 murder trial in Androscoggin County Superior Court in Auburn.

Roberts was convicted and sentenced to 55 years in prison.

The Maine Supreme Judicial Court released its unanimous ruling Wednesday, saying Roberts’ Sixth Amendment rights had not been violated.

He shot Melissa Mendoza, 29, of California in his garage at about 1:30 a.m. on Aug. 15, 2005. The couple had been embroiled in a custody dispute over their daughter, Savanna.

Roberts claimed the shooting was in self-defense. Prosecutors said he had lain in wait for Mendoza.

His direct appeal to the state’s law court was rejected by that court in 2008 when it upheld his conviction.

Through his Boston attorney, Rosemary Curran Scapicchio, Roberts later argued at a post-conviction evidentiary hearing in 2011 that he should be given a new trial because his constitutional rights had been violated.

Scapicchio argued that Roberts’ Sixth Amendment right to a proper trial was violated because some members of the public were kept out of the courtroom during trial testimony, as well as during the reading of the verdict.

She also argued that Roberts should have been allowed to decide whether to waive “voir dire” jury selection, which is when prospective jurors are asked questions about potential bias or conflict.

Justice Joyce Wheeler, who presided over Roberts’ trial and post-conviction review hearing, declined to recommend a new trial, but allowed Roberts to argue his case before the high court, which Scapicchio did in September.

Scapicchio argued there were less restrictive means available to Wheeler to have accomplished her goal of restricting courtroom traffic that she found to be disruptive to the jury. Scapicchio said Wheeler only allowed the public to enter the courtroom during breaks in witness testimony.

Assistant Attorney General Donald Macomber said he agreed with Wheeler’s decision to take steps to limit the courtroom traffic during testimony, which she had correctly reasoned had been disruptive to the jury, thereby hindering its ability to focus on the witnesses.

Macomber also noted that Roberts hadn’t objected during jury selection to an individual voir dire in judge’s chambers and had, in fact, attended that portion of it.

Writing for the high court, Justice Warren Silver said, “This appeal requires us to weigh Roberts’s personal right to a fair and public trial with the trial court’s responsibility to manage the proceedings and maintain order.”

The Sixth Amendment’s public trial guarantee “is for the benefit of the accused; that the public may see he is fairly dealt with and not unjustly condemned, and that the presence of interested spectators may keep his triers keenly alive to a sense of their responsibility and to the importance of their functions,” Silver wrote.

Regarding Roberts’ claim that he should have been allowed to decide whether to waive public voir dire, Silver wrote: “Trial counsel’s decision (that it be held in chambers) represented a thoughtful and practical strategic choice designed to elicit the most candid responses from potential jurors, thus providing the defense team with the information it needed to select a jury in a manner that would best protect Roberts’s interests.”

Attorney General Janet Mills weighed in on the high court’s decision Thursday, saying in a news release that she was pleased the court had upheld the lower court’s decision.

“The Court concluded that his arguments did not raise a likelihood that the outcome would have changed the verdict and that they did not merit a new trial,” she said.

“This case is the very definition of a cold-blooded killing, yet another tragic act of domestic violence,” she said. “We are very pleased that the Court has rejected this bid for a new trial and that Mr. Roberts will continue to serve out his lengthy sentence. My heart goes out Melissa’s family and I am glad they will not have to endure the emotional burden of a second trial.”

cwilliams@sunjournal.com