BUFFALO, NY (WKBW) -- Luke Wright did not like it when his half-sister Laura Cummings stared at him.
"He was really mad," said prosecutor Kristen St. Mary during opening statements of Wright's rape and incest trial, describing an incident on the final day of Laura's life.
"[Luke] took a medium pan, filled it with water, put it on the stove, turned the stove on and when the water was boiling he threw it all over Laura's face," St. Mary said.
Cummings, 23, suffered serious third-degree burns as a result.
Cummings, just under five feet tall and barely 100 pounds, was severely disabled, both physically and mentally and could not verbally communicate well.
Instead, she would stare at her older brother.
Wright would respond with anger, St. Mary told jurors, sometimes covering his half-sister's head with a hood.
"You will hear in explicit detail from his own words how he tied Laura to a chair in his bedroom and forced both vaginal and anal intercourse on his sister," said St. Mary. "This became a regularity."
Defense attorney John Nuchereno told jurors that Luke Wright is in the courtroom in body, but the status of his mind is up for debate.
"You'll find that the mind of Luke Wright is not the mind of what we would consider a normal human being, the kind of mind that each of us may well take for granted," said Nuchereno.
Wright was found fit to stand trial, but Nuchereno is using an insanity defense. He describes Wright as retarded with a traumatic brain injury.
"It will help explain in part why someone is Luke's shoes was incapable of doing what a normal person would have done," said Nuchereno.
The first witness was Dr. James Woytach, the forensic pathologist who found more than 30 external injuries on Laura Cummings' body when he performed an autopsy one day after her death.
The third-degree burns to her face and mouth would have required immediate medical attention, he told the jury.
Cummings was killed by her mother Eva Cummings, 51. Eva Cummings is serving a 52-years-to-life prison term.