KIRKWOOD, Mo. — For Bill Arnold, his older sister Karen was always one he could look up to. She was 14 years older and helped raise Bill when their mother died.

“Somebody that I could go to for advice or whenever I needed to help me out with problems,” Bill said.

The two kept close, still talking or texting almost every day. They spoke the night before she died.

“Still can't believe it. Shocking. I don't want to believe,” Bill said.

Wednesday, Karen Arnold, 64, was found dead in the front room of her apartment in the Meacham Park neighborhood of Kirkwood.

Karen’s family said her murder could be related to the death of her teenage grandson, Shelbyon Polk. Polk was killed last year in St. Louis.

“She loved him like her own son. She was really close to her grandson,” Bill said

Bill said Karen was tireless, trying to find out who killed Polk. She would ask for leads and tips on social media.

“She wasn't going to stop looking into it and seeking leads. I think they know that,” Bill said.

Now, Bill finds himself in the same position: wondering whether he’ll see justice for his sister.

“Please, if you know anything, see anything, call police. If they do this to an innocent, older lady, they'll do it to anyone,” Bill said.

If you have any tips or information, call Kirkwood police at 314-822-5858.