Police affidavit says son was covered in blood when officers arrived at west El Paso home and found his parents fatally stabbed

EL PASO, Texas -- A police affidavit obtained by ABC-7 on Friday offered new details as to what happened early Thursday when a couple was found stabbed at a west El Paso home in the 7500 block of Medano near Franklin High School.

Police said the couple's 35-year-old son, Benjamin Duncan, stabbed both his parents to death before calling 911.

Dispatchers said they heard Duncan frantically asking for an ambulance, saying: "I stabbed my two parents, I need an ambulance. Dad, Dad, Dad, Mom." Duncan was arrested at the scene of the crime, police said. When he opened the door, he put his hands in the air and was covered in blood, according to the affidavit.

Those who knew victim Julie Duncan said she was a kind woman who greeted others with a smile. She worked for the Regional Day School Program for the Deaf at Hillside Elementary, Ross Elementary, Austin High School and Burges High School. Those who worked with her were left speechless after hearing about the crime.

"You know them and when you hear something like this it's tragic, you feel bad for her friends past and present and for what the future could have been," said Debi Marks-Dent, a former co-worker.

She described Julie as a dedicated speech therapist who truly cared about the children she helped.

"It's horrible and I think it makes it more horrible because you know the face, you know the name, you know the person. You remember them smiling at you and now they are not," Marks-Dent said.