Michael Slager, the former North Charleston policeman sentenced to 20 years in prison for Walter Scott's shooting death, indicated Wednesday his plans to appeal that punishment.

Slager was sentenced Dec. 7 but U.S. District Judge David Norton has not filed a written order laying out the details and reasons for the penalty.

In paperwork Wednesday, the former lawman's attorney, Andy Savage of Charleston, asked the court clerk to file a notice of appeal once that order comes through. Such notices typically do not state a defendant's reasons for appealing.

"There are issues in the sentencing proceeding that we are concerned about," Savage said Wednesday. "But no decision will be made as to exactly what we will do or what we may appeal until we have time to thoroughly analyze the sentencing order."

Slager, 36, pleaded guilty earlier this year to violating Scott's civil rights by shooting at the black motorist eight times as Scott ran away from a confrontation. His underlying offense in the killing was deemed to be second-degree murder instead of manslaughter, the judge found earlier this month.

That ruling laid the groundwork for the lengthy prison sentence that surprised many observers and advocates who dubbed the case a civil rights triumph amid nationwide scrutiny of police uses of force against black men.

Slager remains at the Charleston County jail awaiting word of where he will serve the time.

He pulled over Scott's car in April 2015 for a broken brake light and soon ran after the driver who had jumped out. They got into a struggle, the officer said, over control of his Taser. Scott, 50, tried to use it against him, Slager would tell investigators.

A bystander's video showed Scott turning around and running away as Slager pulled his pistol and fired until he fell. Scott was hit five times.

Slager was tried for murder in state court, but a jury couldn't agree whether he had committed a crime. A mistrial was declared.

After Slager's plea to the federal charge, Norton heard testimony during a four-day sentencing hearing earlier this month. Slager's lawyers said the officer made the initial decision to shoot and defend himself but got carried away.

Norton decided that Scott's misconduct in evading arrest didn't warrant Slager's reaction and that Slager later misled investigators about his justification for the shooting.

An appeal was expected. While his plea agreement bars an appeal of his conviction, Slager can challenge the penalty.

In issuing the punishment, Norton mentioned his consultation with his wife, a pathologist, while reviewing Scott's autopsy. Slager's attorneys objected to the judge using information from outside the courtroom in fashioning a sentence, but Norton said they would have to take up the issue with an appeals court.

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Reach Andrew Knapp at 843-937-5414. Follow him on Twitter @offlede.

Andrew Knapp is editor of the Quick Response Team, which covers crime, courts and breaking news. He previously worked as a reporter and copy editor at Florida Today, Newsday and Bangor (Maine) Daily News. He enjoys golf, weather and fatherhood.