Timothy Gregory, who faces aggravated battery and arson charges, was ordered held in lieu of $2 million by a judge. Gregory appeared via closed-circuit TV and did not speak as prosecutors recounted the attack.
The victim, 32-year-old Amanda Zelko, remained in a medically induced coma Monday due to her head injuries. She identified her attacker.
Prosecutors said that Zelko was at home when Gregory hit her in the head, pushed her into the bathroom and tried to burn her house down.
Gregory was arrested at the scene. It was immediately unclear what prompted the attack.
Joliet police said they are still investigating and more charges are possible.
Good Samaritan Ryan Flannery was driving past the victim's home Saturday afternoon in the 1000-block of Infantry Lane when he saw her outside in trouble.
"The scariest part was when he was walking towards me because I think that he thought she was still inside and how did she escape and he wanted to drag her back and finish off the job," Flannery said.
"I asked, 'What happened? What happened?' She started screaming, 'The house is on fire. He tried to killing me,'" Flannery said. "She was like, 'He hit me with a hammer. He tried to light me on fire.'"
Flannery went to his trunk and grabbed a welding hammer and told the man to "stay back."
Zelko's mother, Linda Zelko, said she is thankful that Flannery was there to help her daughter.
"There is kindness in the world ... people are kind and caring and stopped and took the time to help my daughter in her time of need," Linda Zelko said.
Flannery said: "I hope she recovers and I hope he rots in jail. Nobody should ever go through that."