AMITY, Ind. -- An Amity family who claims a local bank mistreated their 90-year-old mother is taking aim at the business with a sign.

Stephen Glassburn and his brother erected an 8-feet tall sign a month ago in the front yard of the home of their mother, Frances Glassburn, accusing Mutual Bank in Franklin of taking advantage of the woman who suffers from Alzheimer's disease.

The Glassburn family told 6News' Derrik Thomas that a contractor offered to replace parts of the woman's roof for $48, but then altered a check she wrote him to make it $4,800.

Stephen Glassburn said he is upset that the bank would cash the check, even though there were insufficient funds in his mother's checking account.

"How did they know they were talking to mom, or actually did call her? They can't explain that to us," he said. "Plus, she never signed a waiver for an overdraft to take money out of her savings."

Bank officials said they were very careful to verify that Frances Glassburn had indeed intended to write the large check.

"I believe the bank went beyond its normal due diligence on this. We really went out of our way on this thing," said Mutual Bank President Robert D. Heuchan. "Again, I can't disclose the clear instructions from the customer."

The Johnson County Sheriff's Department has been investigating the contractor accused of forging the check. They are following leads that he may be incarcerated somewhere in Tennessee.

The Glassburns said they are considering hiring an attorney to fight the case, but said that would cost another $3,000 to $5,000, on top of the $4,800 they've already lost.