Prosecutors say David Tarloff knew exactly what he was doing when he killed psychologist Kathryn Faughey in her office in 2008.
Tarloff admits he killed Faughey while intending to rob her office mate, but his defense team has consistently argued he's not mentally stable enough to be held responsible.
A jury deadlocked last year after a 2010 trial attempt floundered during jury selection because of Tarloff's unstable behavior.
Tarloff targeted a psychiatrist who hadn't seen him in 17 years, he thought he could get $40,000 or more with the doctor's ATM card, and he believed God had given him the OK to do it for his mother's sake, defense attorney Frederick Sosinsky said.
"This is an absolutely crazy, insane, delusional way of thinking," Sosinsky said in his opening statement as Tarloff, 45, who has previously been prone to courtroom outbursts, watched quietly.
Faughey, 56, had never treated Tarloff, a promising high school student who was diagnosed with schizophrenia while in college. Faughey's officemate, Dr. Kent Shinbach, had had Tarloff hospitalized the first time, in 1991, but hadn't seen him since.
Hospitalized more than 20 times over the years, Tarloff has recounted seeing the "eye of God" on the kitchen floor and interpreted pieces of paper on the street as a special message from God, according to court papers. And by 2008, he'd become fixated on his fears that his mother was being mistreated in a nursing home.
Looking to stick up Shinbach, Tarloff encountered Faughey first. He slashed her 15 times with the cleaver and fractured her skull with a mallet.
"I didn't go there to hurt anybody," Tarloff said later in a video-recorded statement. He said he reacted out of a belief that Faughey "was going to kill me," though he also has told doctors he thought she was maliciously aligned with Shinbach.
Prosecutors acknowledge Tarloff's sickness but say he acted as a scheming criminal.
Tarloff bought weapons for the robbery, called ahead to find out the office's hours and quickly volunteered a lie about what he was doing in the building when someone passed him in the stairwell, Krutoy noted. After the attack, Tarloff successfully avoided authorities for a few days before police identified him through fingerprints.
Some of Faughey's six siblings have attended every one of Tarloff's court dates, and five were there Monday as prosecutors outlined the brutal details of her death for a new jury.
"We have to relive Feb. 12, 2008, every single day of these trials," one of her brothers, Michael Faughey, said afterward.
If convicted, Tarloff could face up to life in prison. If his insanity defense succeeds, he could be held indefinitely in a psychiatric hospital.
(The Associated Press contributed to this report)