Johnny Gaskins said the items were found in a 2009 Dodge Durango used by Grant and Amanda - and were apparently overlooked by police investigators.
Amanda Hayes pleaded not guilty last month to murder and "accessory after the fact of murder" charges, almost two months after a jury found her husband Grant guilty of first-degree murder in the killing and dismemberment of Ackerson - who was the mother of his two oldest children.
Grant Hayes blamed Amanda for actually killing Ackerson - saying he only helped dispose of the body. Gaskins said at Thursday's status hearing that he intends to prove Grant was the killer.
Prosecutors say the couple murdered the 27-year-old at their Raleigh apartment in July, 2011 during a long-running custody dispute. Prosecutors say they chopped up Ackerson's body, put it in coolers, and then drove them in a rented U-Haul to Amanda's sister's house in Richmond, Texas, where the body parts were dumped in a nearby creek.
Court documents obtained by ABC11 Monday revealed Gaskins petitioned the court to take custody of the SUV the couple allegedly drove to Texas for 48 hours to examine it.
Gaskins received the Durango on Saturday and returned it to the Raleigh Police Department Monday before noon.
Following the inspection, Gaskins filed a motion that stated while he had the SUV he found " ... a physical item that is critical to the defendant's ability to properly and adequately defend herself at trial."
Gaskins also wrote, "It appears that the officers of the Raleigh Police Department and the State of North Carolina failed to recognize the item for what it was."
But prosecutors said Thursday they doubt the items were overlooked by investigators, and there's probably a logical explanation. Wake County Assistant DA Becky Holt told ABC11 she's not even sure the suit and gloves are new evidence, and they could have been left by a crime scene investigator.
"We don't know exactly all of that now. We're going to have, you know, the right authorities look at this and do any testing that the defense wants done and, and we'll see where we go," she offered.
Late Thursday, prosecutors said that the hazmat suit and gloves were worn by Raleigh police investigators who were moving the vehicle from CCBI to impound. They say the items were worn to keep from contaminating evidence and then left in the vehicle to "make sure that materials involved in the investigation of this case, no matter how insignificant, were preserved." They want the judge to DENY the defense motion for testing.
Amanda Hayes' trial is set for Jan. 20. Grant Hayes is currently serving a life sentence in prison.