An elderly couple was found slaughtered in their Phoenix home. Police still don't know who or why.

An elderly Phoenix couple was slaughtered, and police remain puzzled years later about why and who killed the couple.

On July 2, 2014, William Singer, 81, and Barbara Singer, 64, were found murdered in their home.

Phoenix police Lt. Lois Weiss said in a video the department made and shared on social media that the couple was “brutally” killed in their home.

“This man was slaughtered and left like a piece of trash in his chair,” Weiss said. Police followed a trail of blood to another room, where they found Barbara Singer dead.

Investigators traced the couple’s movements in the days before the murder and found the duo at an ATM withdrawing large amounts of money. Weiss said that was unusual for the couple. Police believe the couple got the money, were taken back to their home and murdered.

“We just don’t understand why them,” Weiss said. “Why target them?

Neighbors Joanne and Scott McLellan described the Singers as a loving couple who were honest and good friends.

Both Barbara and William worked in the medical field. William had kids and grandchildren from a previous marriage. William Singer Jr. told AzFamily.com that he flew in from Indiana after the murder. He said there was no reason for anyone to kill the couple.

"They would have given anyone anything. So, this doesn't make any sense," he told the news outlet.

Police have released photos of “persons of interest” in the case but so far have made no arrests in connection to the couple’s killing. The persons of interest were seen days before the murder knocking on a neighbor’s door and claiming they worked for the cable company, according to AzFamily.com.

Phoenix cops are asking for anyone with information to come forward and call (480) 948-6377. A reward of $5,000 is being offered in the case.

“You know these people were good people and you know they didn’t’ deserve this,” Weiss said. “Nobody deserves this.”