TAMPA — In the months after she was charged with murdering her mother and stepfather, Nicole Nachtman recounted her childhood and teen years for a psychologist. What emerged from the more than 30 hours of interviews was a portrait of a depressed and anxious 21-year-old who had the maturity of a child.Kathleen Heide, a University of South Florida criminology professor and psychologist, testified in a Tampa court Wednesday that Nachtman lived in fear of her own mother, was emotionally stunted from years of abuse and neglect and showed signs of a serious mental illness."There is substantial evidence that she had obvious mental health issues for years," Heide said.Nachtman, 24, faces two counts of first-degree murder in the deaths of Myriam and Robert Dienes. The couple was found Aug. 20, 2015, after deputies responded to a report of gunshots at their Carrollwood home. Heide's pretrial testimony is being used by defense attorneys to argue that Nachtman suffered from "battered child syndrome" and was mentally ill when the murders occurred. They've asked a judge to allow Heide to appear as a witness at Nachtman's trial, scheduled for later this month.Nachtman, clad in an orange jacket, jotted on a notepad, quietly sobbing at times as the doctor testified.Heide's report drew from interviews with the defendant and her family members and more than 500 pages of documents detailing Nachtman's life. She described abusive acts that Myriam Dienes was said to have inflicted on her daughter.There was psychological abuse, the doctor said. Nachtman's mother badgered her about her weight. She forced her to exercise and, at one point, made her undergo liposuction.There was verbal abuse, Heide said. Dienes was said to have referred to Nachtman as “a (expletive) worthless daughter” and to have called her “an overweight skank.” At her high school graduation, Dienes was said to have grabbed her daughter by the arm and told her she was "an embarrassment to her."Heide said there also was physical abuse. Nachtman reported her mother hit her with a plate. Her mother kicked her. Her mother threw a plastic radio at her. Her mother slammed her head into a table when she had done nothing wrong.Her problems began early in life. When she was a baby, she lived with her biological father, Ronald Nachtman. But she soon became a pawn in a bitter custody dispute, Heide said. The fighting, Heide said, constituted emotional neglect.“These are parents at war,” she said. “They’re not functioning in terms of the best interests of the child.”Over the course of her life, Nachtman attended 13 different schools. The moves made it difficult to form friendships.All of it, Heide said, contributed to Nachtman's delayed maturity. When the doctor first interviewed Nachtman eight days after her arrest, she came across as somber and depressed. But her mood could shift rapidly, with her becoming talkative about movies and Japanese anime. She told a joke. She acted like the psychologist was her best friend."It was the behavior of a child," Heide said. "This is not somebody who is functioning where you would expect her to be functioning."Nachtman enrolled at Florida State University in 2014. People who knew her there said she often kept to herself, spent hours on computers and had poor hygiene, Heide said. Her grades began to slip.Nachtman's older half-brother, Joseph Carey, testified via phone, backing up much of the doctor's testimony. He described his own concerns, when his sister reached college age, that she was incapable of paying bills, attending classes, shopping, and caring for herself.Prosecutors say Nachtman told police she began thinking about killing when she encountered problems paying for campus housing.On the night he learned his mother was dead, Carey said he called his sister. He said he believed it was a murder-suicide. He told her everything would be okay, that the family loved her.She said she was going to miss him. He asked what she meant. "You can call me a beast," he said she replied, "but don't call me a monster."He asked again what she was talking about. She whispered."I shot them."She began to cry. He said she told him she'd been having nightmares and spoke of "screaming in her head." It subsided, she said, right after she shot her stepfather.Afterward, she drove back to FSU, Carey said she told him. In her dorm room, she began to think about killing her mother, too.In the hallways, she noticed signs that said things like, "You can do it.""She took it as a sign from God basically saying she needs to go finish it," Carey testified.He said his sister told him she drove back to Tampa and waited for her mother to return from a work-related trip. She got "cold feet" and tried to slip out a window as Dienes arrived. Dienes confronted her. Nachtman said she blacked out. The next thing she remembered, she was driving back to Tallahassee.Contact Dan Sullivan at [email protected] or (813) 226-3386. Follow @TimesDan.