Updated at 6:30 p.m.

CLEVELAND — Amber Hill suffered with bouts of depression, hallucinations and suicidal thoughts for four years before she drowned her two daughters in a bathtub in her Cleveland apartment.

A psychologist hired by the defense and a court psychiatrist testified Thursday before a three-judge panel in Cuyahoga County Common Pleas Court that Hill was so deeply depressed the day she killed Janelle Cintron, 4, and Cecess Hill, 2, that she did not understand that what she was doing was wrong.

Hill, 23, is charged with aggravated murder for the girls' deaths and could face the death penalty if convicted. She pleaded not guilty by reason of insanity.

Prosecutors rested their case against Hill Thursday morning -- the third day of the trial which is being decided by the judges, not a jury. The prosecution did not call any witnesses to testify to Hill's sanity. But they have indicated they plan to call two rebuttal witnesses this morning.

Reading from a transcript of his interview with Hill, psychologist John Fabian said Hill saw the children as an extension of herself and wanted to put them all out of their misery.

Hill described to the psychologist her version of what happened Oct. 1, 2007, the day she killed her daughters. She spent most of that morning crying in her bedroom before she drew a bath for the girls and helped them into the tub.

As she stood watching them with her arms crossed, Hill told the doctor, she momentarily considered getting them dressed and ready for the day. But then she heard the voices in her head. She had been hearing them for months -- her mother asking her what she was going to do with her life; her boyfriend, Jaime Cintron, calling her name; and another voice that she described as demonic encouraging her to kill herself.

On that day, however, the voices told her to "do it!" -- to drown her children. And she complied.

First she held Janelle's head underwater. The girl kicked and thrashed, Hill said, until her little body went limp.

As she held Cecess down in the tub, the toddler looked up through the water at her mom, Hill told the psychologist. But she was smaller than her sister and struggled less.

Hill said she killed her two girls as a way to get help for her deepening depression without killing herself.

"I thought this was how I could get help," Hill said during the psychological analysis. "And I needed to know that people loved me. I felt like part of my brain was gone."

Dr. Sherif Soliman, a court psychiatrist who evaluated Hill, told the judges that Hill's severe depression spurred psychotic symptoms, such as auditory hallucinations.

Hill struggled with the delusions and believed that because she was suffering, her daughters were suffering too, Soliman said. She wanted her children to feel the peace she could not. She did not expect to be punished for her actions and was surprised to learn that the police detective who interrogated her was not there to help her, Soliman said.

Hill told Soliman during her psychiatric evaluation that as she returned to her apartment after calling Cintron from a pay phone to tell him what she had done, she stopped at the mailbox to pick up her mail.

"She saw a check in there and thought about cashing it later that day," Soliman said. "She didn't know that what she was doing was wrong."

Prosecutors pointed out during their cross-examination of the doctors that Hill shut the shower curtain after drowning her children, indicating that she didn't want to see them and was disgusted by her actions.

Fabian said Hill explained to him that she didn't want to see her girls exposed and closed the curtain to keep them safe.

"There is a theme of misery and of benevolence -- of saving them from her own psychotic and depressed demons that she was struggling with," Fabian said. "She thought she had to save her children from her own death or suicide."