"Kathy's skull had been crushed and fragments were pushed into her brain," said prosecutor Trish Jacobs.
Jason Williford has pleaded not guilty in the 62 year old's killing at a home in Raleigh. He could face the death penalty if convicted.
Police have said Williford attacked Taft inside a home on Cartier Lane in the late night hours of March 5 or the early morning hours of March 6. She died at WakeMed a few days later.
The former member of the State Board of Education and her sister were housesitting at the Raleigh home while Taft recovered from a surgery.
Her sister found her bloodied body and lab results revealed the state school board member had been sexually assaulted and had a deep cut on the back of her head.
In her opening, Jacobs said Taft's killer left semen on the bed where she was found. She said DNA was a match for DNA found on a cigarette linked to Williford.
Police said Williford, a Raleigh musician, lived in an apartment around the corner from the home where Taft was staying when she was attacked.
In his opening statement, defense attorney Ernest "Buddy" Conner said his client is mentally ill.
"He is not right, He has never been right," said Conner.
Conner said a defense physiatrist diagnosed Williford with alcohol and marijuana addictions, plus mood and sexual disorders.
Conner told jurors that his client's diminished mental capacity means that he is not guilty of a premeditated first-degree murder.
Before opening statements Wednesday, Superior Court Judge Paul Gessner ruled on motions from the defense to suppress evidence.
Williford's attorneys argued certain crime scene, hospital, and autopsy photos could be unduly prejudicial. In one instance, the defense contended that Taft lived for a few days and the bruising became worse by the time of her autopsy. They only wanted photos taken right after the attack used.
Prosecutors said the photos were disturbing, but that's the nature of such evidence.
Gessner ruled the photos are not unduly prejudicial and can be used.
The trial is starting with just 12 jury members and two alternates. There are seven women and five men in the main panel and the two alternates are male.
Taft served on the State School Board for 15 years. She also ran unsuccessfully for a state Senate seat in 2008. Prior to that, she served on the Pitt County Board of Education.