50-year-old Mactavish Alexander has been charged with two counts of first degree murder and felony weapon possession. He is being held without bail.
Relatives of one of the victims say they arrived to find 48-year-old Joseph Taylor and 52-year-old Mary Dale dead on Saturday afternoon.
The discovery of the bodies was made on the 4600 block of New Castle Avenue.
Taylor who was disabled relied on the full-time help of Dale, his caretaker.
Delaware State Police have not released the cause of death, but relatives tell Action News it appears both were bludgeoned to death.
Sources say a dumbbell weight was found near the bodies. The gas on the stove was also left on but there was no explosion.
"The investigation is still early and we're investigating all surrounding circumstances into the death of these two people," said Cpl. Gary Fournier.
Relatives say Taylor has the mental capacity of a 10-year-old.
"He's a good person, I love my brother, I just don't understand why someone would do something like this," said John Taylor, the victim's brother.
Taylor's sister became concerned when he did not show up for his Saturday morning bowling league at the Bowlerama nearby. She was unable to reach him by phone.
"He was kind and gentle. He would do anything for anybody. He was just great, loved everybody. Go to church every Sunday, Bowlerama every Saturday, that's what he likes," said Edith Taylor, the victim's sister.
Friends and relatives are having a difficult time understanding why someone would do this to a mentally challenged man and his caretaker.
"I mean he stayed in church constantly, I mean nobody in the whole community could say anything negative about Joey," said Jimmy Jones, the victim's friend.
His pastor at People's Baptist Church says Taylor was very religious.
"He was a young man that loved the Lord, lived a good life with the Lord. Prayed every day, every night and he didn't deserve this. Whoever did it he just didn't deserve it," said Pastor Rodger Woodard.