CHICAGO (CBS) — A Chicago woman is asking for help to find her missing brother after he disappeared from a southwest side hospital earlier this week.

CBS 2’s Meredith Barack has more on the desperate search for the 68-year-old man.

Joseph Overstreet was last seen at Ingalls Memorial Hospital on Monday. His sister said he was released, walked out or got into a car with someone. She said none of that should have happened, as he’s mentally disabled and she’s his legal guardian.

She’s now desperately searching for Joseph, while awaiting answers from the hospital as to how it could have happened.

Betty Hammond said she wants answers as to what happened to her brother, Joseph Overstreet. She said he was brought to Ingalls Memorial from Crestwood Terrace on Monday morning, and by Monday night, he was missing.

“I called the nursing home Tuesday morning and he had not arrived back at the nursing home. So that’s when we knew that there was a serious problem,” Hammond said.

Hammond, who is her 68-year-old brother’s legal guardian, said someone dropped the ball.

“Is he safe? Is he okay? Did somebody harm him,” asked Hammond. “So me not being notified, letting me know that something happened that shouldn’t have happened.”

She said police in Harvey were notified. And she also spoke with executives from the hospital who admitted to her something happened. But what exactly remains unclear.

“How did it happen? How was the guardian not notified, or even the nursing home? So yes, they are investigating it,” Hammond said.

In a statement to  CBS 2, Ingalls Memorial said it hopes Joseph is found safe, but cannot comment due to patient privacy laws. In the meantime, Betty Hammond said she will not stop searching.

“I have not been able to sleep. It’s been mind boggling, because I know he’s like a child,” Hammond said. “I just want him returned safely. That’s all I want. We’ll find Joe. We’ll find him.”

CBS 2 also reached out to Crestwood Terrace for comment It said it is not speaking to the media.