WARREN, Ohio (WYTV) – Prosecutors continued presenting their case on Tuesday against the man accused of stabbing a 71-year-old to death over three years ago.

The state called three witnesses to testify against 23-year-old Patrick Heltzel, who is charged with aggravated murder.

Milton Grumbling was found stabbed to death in his Warren Township home in April of 2013. Heltzel said he was insane at the time of the alleged crime.

Two of the witnesses were forensic scientists with the Bureau of Criminal Investigation. The third, Dr. Thomas Gazley, is a psychologist who does forensic evaluations for the courts.

Assistant Prosecutor Chris Becker called Gazley to the stand, hoping to chip away at Heltzel’s defense that he is not guilty by reason of insanity.

“To qualify to present a not guilty by reason of insanity plea, has to present severe mental defect which is an intellectual-deficit, or a severe mental disease which is a reversible mental illness and that because of that severe mental disease, the person does not know the wrongfulness of their acts,” Gazley said.

He evaluated Heltzel four times between August of 2013 and January of 2014. Their last meeting was eight months before Heltzel was found to be incompetent to stand trial.

In those interviews, Gazley found Heltzel did suffer from a severe mental disease, but concluded that he still understood the wrongfulness of his acts.

“I believe he does suffer a severe mental disease but I also think that at the time of the offense, in spite of his severe mental disease, he knew that the acts committed were wrong.”

His reasoning for this opinion was that Heltzel fled the scene, leaving the state to visit his mother in North Carolina. Gazley also said that Heltzel understood his Miranda rights, requesting an attorney immediately after his arrest two days after Grumbling was found dead.

Attorney John Juhasz argued that all of those meetings between the defendant and Gazley took place before Heltzel was restored to competency in 2015.

“After he was restored to competency, you did not go back and re-interview the defendant concerning events that happened at the time,” Juhasz said.

Gazley said he did not re-interview Heltzel, and that he didn’t know he was found incompetent.

Testimony is expected to resume Wednesday morning.