Mohegan — Police have charged a Massachusetts woman with fraudulently using nine Mohegan Sun Player’s Club cards to redeem $70,430 in slot play bonuses over the course of six months.

Lisa Onderdonk, 48, of Auburn, Mass., was charged Monday on a warrant with first-degree larceny.

The warrant says Onderdonk began fraudulently redeeming the bonuses after her ailing pet cat left her with a $7,000 veterinarian bill. When it seemed no one was noticing her actions, the warrant says, Onderdonk began going twice weekly and using the money to help out with other bills. 

Police began investigating the incident in February, when a card member realized his account had been used to redeem $2,500 in slot play bonuses while he was out of the country.

At Mohegan Sun, those who have Player’s Club accounts earn points for their gaming activity. With enough points, members become eligible for promotions that take place on certain days. To redeem a promotion, a person must use his Player’s Club card and personal identification number on the correct day, which is advertised in a calendar sent out to all club members.

In his investigation, Detective Thomas Nickerson worked with surveillance analysts to learn when the victim’s card was used. They said they discovered footage of a woman who inserted several cards, including the victim’s, into a slot machine on the night of Jan. 28. Each time, the woman entered the corresponding PIN and played just enough to redeem the bonuses. Nickerson said the woman walked away with $1,545 that night.

Further review of casino footage showed the woman did the same thing 54 times from Aug. 11 through Feb. 3, the warrant says. She allegedly used a total of nine cards in varying combinations and left each trip with between $500 and $2,000.

Nickerson used footage from different cameras to get the license plate of the car the woman drove to the casino. The plate came back to Onderdonk. Nickerson requested a photo of Onderdonk from Massachusetts motor vehicle officials. With it, he confirmed the woman to whom the car was registered was the woman in the surveillance videos.

Police then went to Onderdonk’s Massachusetts home. When they showed up, Nickerson said, Onderdonk not only confessed to the crime, she also explained her method.

The warrant says Onderdonk scoured the casino and picked up Player’s Club cards that had been left behind. She didn’t know the cards’ PIN numbers, so she entered guesses online until one worked, using a spreadsheet to keep track of what she already had tried.

Onderdonk allegedly told police she used her mother’s promotions calendar to learn when to go to the casino, and would wait until 9 p.m. or later to do so. She figured a person who hadn’t redeemed a promotion by 9 p.m. likely wasn't going to, Nickerson said.

Officials set Onderdonk’s bond at $50,000 and scheduled a Norwich Superior Court date for May 10. Police said they did not have a photo of Onderdonk on file.