Wednesday's filing asks a judge to force prosecutors to turn over witness statements and grand jury material tied to the June 7, 2021 killings of Maggie and Paul Murdaugh.
The defense says a 2023 witness told state agents Yemassee Police Chief Greg Alexander was seen with the unrecovered murder weapons and spoke of providing Alex Murdaugh a change of clothes after the shootings.
Murdaugh's lawyers argue that, if accurate, the material was withheld and undercuts prosecutors' 2023 trial theory that Murdaugh alone disposed of the guns and changed clothes after cleaning up.
Alexander, through his attorney, denied the allegations in media reports, while The Post and Courier said it could not corroborate the claims.
The dispute lands ahead of Murdaugh's retrial, set for April 5, 2027, after South Carolina's Supreme Court overturned his murder convictions over jury tampering by former clerk Becky Hill.