TAMPA — Nicole Nachtman's attorneys will be allowed to present testimony that she suffered from battered child syndrome when prosecutors say she killed her mother, a judge ruled Thursday. But the same evidence cannot be used for a defense in the murder of Nachtman's stepfather.Following a day of testimony from a psychologist, Hillsborough Circuit Judge Christopher Sabella said there was nothing to indicate that battered child syndrome was a factor in the killing of her stepfather. He also granted a defense request that the murders of Myriam and Robert Dienes be split into two separate trials.Nachtman's trial in the death of Robert Dienes remained set for later this month.Prosecutors say Nachtman, 24, shot Robert Dienes in their Carrollwood home, then waited a day for her mother to return from a trip. When Myriam Dienes arrived the night of Aug. 20, 2015, Nachtman shot her, too, the state says. Kathleen Heide, a University of South Florida criminology professor and psychologist, testified Wednesday that Nachtman suffered years of abuse at the hands of her mother. The mistreatment stunted her emotional growth and caused her to exhibit signs of mental illness."We know that in her mind, Dr. Heide says she had three choices: kill myself, kill my mother, or be killed," Assistant Public Defender Dana Herce-Fulgueira said in arguments Thursday. "She was so terrified of her mother that she feared for her life."Nachtman's older half-brother, Joseph Carey, backed up much of what Heide said. He also described a conversation with his sister that occurred shortly after he learned their mother had died. He said she admitted to shooting the parents.Carey had said he believed that his sister drove to Florida State University, where she was a student, after the first murder, and returned to Tampa later. But defense attorneys clarified Thursday that there is no evidence that Nachtman went to Tallahassee until after Myriam Dienes died.. Nachtman was arrested in Tallahassee a day after Hillsborough sheriff's deputies discovered the killings.Assistant State Attorney John Terry contended that battered child syndrome can only apply to cases of self-defense. He said there was no evidence that either parent was attacking Nachtman when they were killed.The thrust of the defense's argument was that Nachtman's fear of her mother, and a confrontation that ensued when Myriam Dienes caught her at home, meant that self-defense could be argued. They also said that Robert Dienes did nothing to stop the abuse Nachtman suffered."She perceived Bob as an extension of her mom," Herce-Fulgueira said. "She perceived him as someone who, if mom showed up that day and killed her, was not going to do anything to protect her."But the state said that didn't constitute abuse."There is no evidence of any abuse from Robert Dienes whatsoever," Terry said. "He was just a person who happened to be in the way of who she really wanted to kill, which was her mother."To argue that battered child syndrome influenced the mother's murder, Judge Sabella said the defense would have to lay a foundation for the evidence. That means Nachtman herself would likely have to testify.Contact Dan Sullivan at [email protected] or (813) 226-3386. Follow @TimesDan.