BARRIE, Ont. - It was a "recipe for disaster" when a mentally ill single mother was released from a psychiatric ward with little more than a prescription and sent home alone to care for the daughters she would later drown, court heard Thursday.

Elaine Campione is charged with first-degree murder in the deaths of her two daughters -- Serena, 3, and Sophia, 19 months.

Defence lawyer Mary Cremer told the jury in her closing arguments Campione was so plagued by mental illness that she could not have formed the criminal intent required to convict her of first-degree murder.

She believed she was being followed by people trying to kill her and take the girls away in the months leading up to the killings, and bizarre behaviour included refusing to let one of her daughters touch anything red and claiming she saw aliens, Cremer told the jury.

"It was conceded by the defence that Elaine Campione caused the girls to drown, however the defence maintains that Elaine Campione never planned to deliberately kill her children," Cremer said.

The Crown alleges Campione killed her daughters so her ex-husband couldn't get custody, and then tried to kill herself.

Campione was released from hospital in the summer of 2006 following a nearly one-month stay after a suicide attempt, Cremer said. She had been hospitalized several more times over the previous year, once after a psychotic episode.

After she was released from hospital the last time, Campione was further losing grip with reality and sinking deeper into her paranoid delusions, Cremer said. Her parents were in New Brunswick, she was in the midst of a custody battle with her ex-husband so she wouldn't turn to him or her in-laws for help, and she was worried about her medical records coming out in the custody proceedings, Cremer said.

Campione, "a woman ravaged by mental illness," started to believe she was getting signs from God through Serena that heaven would be a safe place, Cremer said.

She was given a prescription for an antipsychotic, but in the past she hadn't followed through on taking prescribed medications, Cremer said.

"It's clear here how we see that tragedy's about to strike," Cremer told the jury. "This was a recipe for disaster and Elaine, in looking back, really didn't stand a chance."

The trial has heard that the bodies of the little girls were found posed in their mother's bed in October 2006. They were wearing pyjamas and holding hands, and between them lay a photo album and a rosary.

Campione, with her long dark hair in pigtails, wept or fought back tears during much of the closing arguments, during which her lawyer detailed her history of an abusive marriage, and the depression and delusions from which she suffered.

"This mental illness had gripped her and was plaguing her and deprived her of the ability to make rational decisions at the time she drowned her children," Cremer said.

Campione left her abusive husband in the summer of 2005 and went to a shelter with her children, Cremer said. Campione's mother testified her daughter began to fear that people were following her on the orders of her ex-husband and that someone -- even random strangers in the street -- would take the girls away from her, Cremer said.

In downtown Barrie one day Campione began to run after a woman she believed took a photo of her children, Cremer said. She also began to fear she would be "erased," and it would be as if she never existed, Cremer said. She wouldn't leave the girls alone, even with her own mother.

She was admitted to a psychiatric ward in June 2005 and a social worker noted she was having trouble seeing herself and her children as separate entities, which was troubling because she was also suicidal, Cremer said.

Almost exactly one year before the girls died Campione drove her mother to the airport and tried to take a route only making right-hand turns. She wouldn't let Serena touch anything red because she said it represented blood and wouldn't park beside any black cars, Cremer said.

After dropping her mother off she drove to her in-laws' house and ran from room to room talking about seeing aliens.

She was again admitted to a psychiatric ward for postpartum psychosis. A few months later she was back in hospital with an "overwhelming sense of doom," Cremer said.

Days after being discharged she tried to get admitted to a different hospital saying she was having trouble coping, but they gave her a crisis number and told her to see her family doctor, court heard.

Just weeks later in June 2006 Campione attempted suicide and was admitted to hospital for almost a month. Closing arguments continue Friday.