A 91-year-old Long Island woman with dementia had three-quarters of a million dollars stolen from her by a woman entrusted to help take care of her finances, according to prosecutors, leaving the victim's family enraged.

Elizabeth Reilly appeared before a Nassau County judge Wednesday, charged with stealing hundreds of thousands of dollars from Marian Mahlmeister, a former vice president of a bank who had amassed a small fortune.

When Mahlmeister was diagnosed with dementia, she hired a "very, very close friend of hers" who was a prominent attorney to draw up all the legal documents for her, according to Karen Cunningham, a niece of Mahlmeister.

But that trusted friend, who was supposed to handle the finances, passed on the day-to-day work to Reilly, his employee. Prosecutors said that between 2016 and 2020, Reilly drafted 250 checks from Mahlmeister's account and deposited the money into her or her husband's account, in large sums at a time: amounts of $30,000 and $50,000 added sporadically.

"We were confused we were bewildered we were angry, very very angry that this could happen," said Cunningham.

There were also credit card bills, luxury vacations, concert tickets, and donations to a dog charity. In all, the estimated total came out to $750,000, prosecutors said.

The allegations against Reilly are not her first bruch with the law: In 2008, she pleaded guilty in federal court to embezzling $1.3 million while working as a bank employee.

Reilly did not comment to NBC New York, but her attorney said she pleaded not guilty on Wednesday.

"She’s distressed that she’s here, that she’s being accused of this. If there’s any wrong doing she wants to make it right," said defense attorney Mark Gann.

Mahlmeister died in 2021, which has left Cunningham trying to recover her aunt's hard-earned fortune.

"I hope that justice will be served and she will serve time," she said. "What she did was the worst thing someone can do to an old person, who saved their entire lives to make sure they were okay."