Controversial confessions from the Indiana man accused of killing two teenage girls in a forest were played Thursday at his trial. Richard Allen, 55, stands accused of killing Abigail “Abby” Williams, 13, and Liberty “Libby” German, 14, in Delphi, Ind., on Feb. 13, 2017. Allen has pleaded not guilty, even though he confessed to the killings multiple times in recorded phone calls from state prison. His defense team has argued he was not in his right mind when he made the calls. “I did it. I killed Abby and Libby,” Allen said in one such call, according to ABC News. “Why would you say that?” his wife, Kathy, responded. “I know you didn’t. There’s something wrong.” In another call, Allen told his wife, “Kathy, I did it. Do you still love me?” local Fox affiliate WXIN reported. She responded, “Yes, dear, but you didn’t do it.” Allen’s mental state when confessing will be a central question of the trial. Defense attorneys have argued that his mental health declined as he was held in solitary confinement for 13 months. A therapist who worked with Allen, Dr. Monica Wala, testified Wednesday about her experiences with him, the Lafayette Journal & Courier reported. She said Allen gave her specific details about the killings, including that the girls’ throats were cut and that he panicked and killed them after hearing a van. Additional evidence against Allen includes an unused bullet found at the crime scene that matches a weapon found in his home, according to prosecutors. Investigators also said his voice matched a man heard on a video Libby German took minutes before she was killed. The trial, which began Oct. 14 with jury selection, is expected to last for a month.