Hayes is charged with torturing, abusing and killing Calhoun, his girlfriend Corrine Baker's son, back in April.
Judge John Conover found Hayes competent to stand trial and denied his request for a second, independent evaluation.
Baker's 16-year-old sister says she went to the couple's apartment Sunday, April 11. She went with friends who were buying marijuana from Hayes.
She says she just wanted to see her nephews. The teen says she did see Calhoun. He was on the floor on his back and she had a feeling he was dying.
"Brandon tells me Dominick got beat up by friends and to open the door and look at him," she said. "I opened the door, looked at him and shut it.
"He was covered with blankets. All I could see was his face and it was bruised and I was scared and I didn't know what to do."
Christine Baker says she briefly talked to Hayes.
"I was staying calm until I could get out of there because I was in a dangerous situation and I knew I was in a dangerous situation," she said.
Christine Baker then "bolted," she says. She says she headed outside to call Calhoun's grandfather, Rick Calhoun.
At the hospital the next day, Dr. Brian Nolan examined the boy before he was taken off life support.
"What was unusual about his exam is the extent of the injuries to his genitalia," Nolan said. "They were so swollen, so bruised, and I'd never seen those type of findings on a child."
According to Nolan, the extent of Dominick's injuries -- including the bruises and a severe burn on his hand -- upset experienced doctors and nurses to the point that they had to speak with psychologists.
"I'd say it's one of the worst (cases) I've seen," Nolan said.
Investigators say Calhoun's 8-year-old brother witnessed days of that abuse. He will testify next week.
Conover ruled Hayes will be in a different room when the boy is on the stand. A social worker testified the boy is "deathly afraid" of Hayes.
