Authorities charged a man Sunday with killing his parents with a garden hoe and burying their bodies in their backyard cesspool.

James A. Soares, 24, of Warren, did not enter a plea when prosecutors arraigned him at the state police barracks in Lincoln with two counts of murder in the deaths of James A. Soares Sr., 60, and Marian Soares, 53.

He was being held overnight and was to be formally arraigned in district court Monday. A spokesman for the state police did not know whether Soares had a lawyer.

Police would not comment on a motive but said they believe Soares attacked and killed his parents July 9 with a heavy digging tool known as a grub hoe. Police said he then dragged their bodies into an in-ground cesspool at the family's home in Warren, a small town southeast of Providence. Soares lived with his parents.

"It's incomprehensible to think that someone could kill someone that brought them into the world," police Maj. Steven O'Donnell said.

The couple had been reported missing July 15 after they didn't show up for a family reunion.

On Saturday, police used a backhoe to dig up the Soares' backyard and found the bodies. O'Donnell said the grub hoe was found under the senior Soares' body.

Police said the younger Soares was the prime suspect early in the investigation, based on police interviews. He was taken into custody Friday.

Police would not comment on whether Soares confessed and said the investigation was continuing.

In 2002, the elder Soares pleaded guilty to a federal charge of being a felon in possession of firearms. He was sentenced to probation and home confinement.

Click here to read more on this story from MyFOXProvidence.com.