Marcy Cruz, half of the pair charged with attacking Irish student Natasha McShane and her friend Stacy Jurich in Chicago on April 23, was not taking her medication at the time of the attack.

Cruz, 25, was being treated for anxiety issues and bipolar disorder.

Police say she had not taken her medication when she sat in a nearby van and watched as Heriberto Viramontes beat McShane and Jurich over the head with a baseball bat.

Edwin Cruz, Stacy’s father, described Cruz as mentally unstable. He also said that she tended to be unaware of the consequences of her actions.

“She's not all there in her mind,” he said.

In preliminary reports, Viramontes and Cruz were described as a couple. However, Josue Espinosa, Cruz’s boyfriend, has come forward to say that though Viramontes is the father of Cruz’s two children, there is no romantic involvement.

He said Cruz is a “good person,” and Viramontes was just manipulating her.

Edwin Cruz was shocked after he saw the report of the attack on TV.

“Who could have done this? And then (a few days later) a brick wall comes crashing down on me,” he said.

“It's very sad, it hurts all of us."

That said, he believes that his daughter should not be incarcerated.

Viramontes and Cruz appeared in court for the first time together on Monday. They were both charged with aggravated battery and armed robbery.

Though Viramontes allegedly held and swung the bat at the girls’ heads, the prosecution is saying that Cruz is just as responsible and let the attack happen.

When leaving the court the two inmates looked back towards their families, but they did not acknowledge one another.