David Marble sits in a Portland courtroom in this July 18, 2018, file photo.

A New York man found guilty of murdering an Augusta couple in 2015 has requested a new trial, claiming that legal errors and flawed evidence tainted the case against him.

Last month, a Cumberland County jury returned two guilty verdicts against David Marble Jr. for the Christmas morning killings of Eric Williams and Bonnie Royer.

But Marble’s lawyers claim that jurors should never have been allowed to see an important piece of evidence, and that one of the state’s key witnesses was unreliable.

“The trial generated a number of issues, from admission of evidence we moved to suppress to jury instructions to the sufficiency of the evidence to convict,” defense attorney Jon Gale said. “We raised all of these issues in our motion, any of which could result in a new trial,”

The case against the 32-year-old Rochester, New York, native was built, in part, on cell phone data corroborated with the testimony Timothy Bragg, who said he was with Marble on the day of the killings.

[New York man guilty of murder in 2015 Christmas deaths of Augusta couple]

Before the trial, Marble’s lawyers argued that the data showing the whereabouts of his phone could not be admitted as evidence because of a June U.S. Supreme Court ruling that police need a warrant to access cell site data. In the courtroom, they sought to impugn Bragg, who was granted immunity to testify, saying he was on drugs when he spoke to law enforcement and may have been pressured by police.

Justice Michaela Murphy rejected the first point and the jury appeared unpersuaded by the second, but Marble’s lawyers reprised them in the request for a new trial, which was filed Aug. 1. It has not yet been ruled on.

They also contend that Murphy wrongly instructed the jury to consider “accomplice liability,” that police did not fully investigate the case, and that the state’s other nonexpert witnesses could also not be trusted because they were granted immunity and had been convicted of crimes “involving moral turpitude.”

[Man charged with murder in Christmas slaying of Augusta couple]

The gun used to kill Williams, 35, and Royer, 26, was never found. Gale has repeatedly argued that there is no physical evidence tying Marble to their murders.

Marble, whose case became part of a 2016 controversy over racially charged comments by Gov. Paul LePage, was also found guilty of illegal firearm possession. He is scheduled to be sentenced Oct. 5, and prosecutors have said they intend to pursue a life in prison.

Deputy Attorney General Lisa Marchese did not immediately respond to requests for comment Monday.

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