Updated

Attorneys for a former South Carolina police officer whose case ended in a mistrial last year want murder charges against him dismissed.

In a motion filed on Thursday, attorneys for Michael Slager argue that prosecuting him a second time on murder charges would violate his constitutional rights.

A judge declared a mistrial last year in the case against Slager after jurors, in 22 hours of deliberations over four days, were unable to come to a unanimous decision on murder or voluntary manslaughter charges. Prosecutors are set to bring a new case later this year.

Slager's lawyers contend the jurors indicated that they'd agreed the former North Charleston police officer "was not guilty of murder, but then could not reach agreement on that voluntary manslaughter charge with two jurors committed to acquit Slager."

Since jurors had been told they couldn't even consider manslaughter without first reaching a consensus that Slager wasn't guilty of murder, defense attorneys argue, a second jury shouldn't even be able to consider murder again. To do so would violate the U.S. Constitution's prohibition against double jeopardy.

Slager, 35, is charged with shooting 50-year-old Walter Scott five times in the back as the black motorist tried to flee a traffic stop in April 2015. The incident was captured by a bystander on cellphone video that was shared online and horrified many.

Slager, who is white, is also charged with violating Scott's civil rights, and a federal trial on those charges is scheduled to begin May 1. His retrial in state court is set for August, although Circuit Judge Clifton Newman has said that could be moved up if under President Donald Trump the U.S. Justice Department opted to drop those charges.

Vice President Michael Pence said on MSNBC in December that he had seen the widely viewed bystander video of Slager shooting Scott and was heartbroken like much of the country, but that the Slager case would be one of many reviewed by the new attorney general.

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Kinnard can be reached at http://twitter.com/MegKinnardAP. Read more of her work at http://bigstory.ap.org/content/meg-kinnard/