It was a horrific crime targeting a beloved Phoenix couple.

“They didn't deserve what happened to them," said Joanne Mclellan. "They were caring, loving, wonderful people."

Mclellan still gets emotional when talking about her friends and neighbors of 35 years, 81-year-old William Singer and his wife of more than 30 years, 64-year-old Barbara Singer.

“It's just one of the saddest things in my life, you know,” she said.

July 2, 2014 police responded to the Singer's home near Bell Road and 35th Avenue in north Phoenix after an at-home nurse found the couple murdered inside.

“Whoever did this was definitely and evil, evil person,” said Cristie Eisentraut, a Phoenix police homicide detective, when she spoke with KTAR about the case in 2015. “I've been to a lot of violent crime scenes and this one I would definitely say was one of the most violent and brutal."

Three and a half years later, the Singer’s murder remains unsolved, officially cold.

Police initially released sketches of two men they identified as persons of interest in the case but later determined the men were not linked to the crime.

“I think somebody knows something,” said Mclellan.

Police believe the couple may have been dead for several days before being discovered.

They later release surveillance footage which showed them individually withdrawing large sums of cash from an ATM near their home.

Detectives say the withdrawals were made 15 minutes apart around 10:30 p.m., which did not fit their routine.

They also said William looked to be under duress.

“It had to be somebody they trusted,” said Mclellan. “They wouldn't just let anybody in their house.”

The Singers were more than just good neighbors to those around them, they were also loving parents and grandparents.

Described as being inseparable, family members have said their only comfort was knowing the couple had left this life together.

“You just think, ‘Why would somebody do this?’ And ‘Why aren't they caught?'” said Mclellan, “It really is sad, really sad. They (the suspects) are living a life and Barbara and Bill aren't.”

Anyone with information is still asked to call Silent Witness at 480-WITNESS (948-6377), or for Spanish 480-TESTIGO (837-8446). As always, callers may remain anonymous and could earn a cash reward.