Steven Avery's attorney, Kathleen Zellner, says she'll file new motion Tuesday in 'Making a Murderer' case

Steven Avery's lawyer said she plans to file a motion Tuesday in the ongoing attempt to fight his murder conviction.

Kathleen Zellner tweeted Monday night, "Tomorrow we are filing Steven Avery’s Third Motion for Post-Conviction Relief. Buckle up."

She had previously tweeted, on July 16, that the new petition would contain "compelling new evidence."

Avery, 59, has been serving a life sentence since being convicted of killing Teresa Halbach, a 25-year-old photographer who disappeared in 2005. His story was featured in the 2015 Netflix docuseries "Making a Murderer," which cast doubt on the motives of police and left many viewers with the impression that Avery and his nephew, Brendan Dassey, were wrongfully convicted.

In June, Avery was moved from a maximum-security prison in Waupun to a medium-security prison about 10 miles away in Fox Lake.

Avery had been at Waupun Correctional Institution but was moved to Fox Lake Correctional Institution, according to the Wisconsin Department of Corrections.

In July 2021, the Wisconsin Court of Appeals rejected several arguments Avery has made over the years, including the effectiveness of his attorneys at trial and the way some of the evidence was handled by prosecutors.

A claim Avery and Zellner raised in April 2021 involving a new witness was not evaluated by the appeals court, which explained in its decision that it had already reviewed Avery's other arguments and that the issue involving the witness "bears little or no relation to those claims already before us."

"This is, instead, a distinct issue that the circuit court should resolve on a standalone basis," the court's decision says.

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The new witness, a delivery driver named Thomas Sowinski, claims to have seen two other men pushing a Toyota RAV4 down Avery Road “toward the junkyard” in the early morning hours of Nov. 5, 2005, according to court documents filed by Zellner.

Halbach’s vehicle, a Toyota RAV4, was found later that day at the Avery Salvage Yard. Sowinski said he realized the significance of what he had seen after hearing what type of car Halbach was driving and where it was found. He immediately reached out to the Manitowoc County Sheriff’s Office, but said a female officer told him: “We already know who did it,” the court documents say.

Chris Mueller contributed to this story.

Contact Larry Gallup at (920) 996-7216 or lgallup@gannett.com. Follow him on Twitter @LarryGallup.

This article originally appeared on Appleton Post-Crescent: Steven Avery attorney Kathleen Zellner says she'll file new motion