In a search warrant, an investigator says the child's body was placed in a bag and then the bag was placed in a plastic container. Sheets were placed over the top of the bag, and then bleach was poured on the sheets to "mask the smell."
A report released Monday by the NC Office of the Chief Medical Examiner in Chapel Hill says Gross died of "undetermined homicidal violence." Finding a more precise cause of death was impossible because of the advanced state of decomposition.
The report also shows Gross had suffered several broken ribs which had begun to heal.
A warrant released soon after his death stated the child had not been seen by family for over a month at the time of the discovery.
It said the child's mother - Sherita McNeil - told the family the child was staying with someone else, when in fact he was not.
The warrant also revealed letters from the child's father Eric Chambers to McNeil were found in the home. It said the letters were threatening and expressed concern about McNeil "getting rid of their son."
McNeil is currently charged with the toddler's murder.