Costa Mesa High School's marching band and its supporters are reeling from allegations that more than $40,000 was stolen from the Band Boosters Club.

Mesa's marching band and color guard were stunned to learn that club treasurer Jennifer Border-Piatti, 50, was arrested Oct. 25 on suspicion of embezzling from the club, said band member Jennifer Bernal, 17, who is also a color guard co-captain.

"Right now, I guess we're all a little shocked," she said. "We all saw her as a really supportive figure."

Principal Phil D'Agostino said the school is still trying to get its arms around the situation, but there is no danger of the marching band ceasing to exist.

"Things are going as well as can be expected," he said. "We're putting some plans together; we're looking at resources we have, ... and we're going to get the band back on its feet."

The Band Boosters Club asked Piatti and her husband, Robert Piatti, to step down as treasurer and president respectively, said Boosters Club member Michael Collier, a former school board member. Robert Piatti is not accused of any wrongdoing.

The Boosters Club is holding a parents' meeting Monday to elect new officers, Collier said.

Border-Piatti's arrest was "strange" after knowing her for so many years, Collier said.

"We're really sad it happened," he said. "It's just an unfortunate thing. It's a tragedy it happened."

After serving a search warrant at her home, Costa Mesa police allege Border-Piatti made credit card purchases and ATM withdrawals from the Boosters account that were not related to club business. Police believe Border-Piatti stole from the club for years.

The marching band relies on fundraisers and community donations to cover many expenses. Tournaments cost about $800 to $1,000, Collier said.

The members have done everything from going door-to-door to collecting spare change to selling candy bars and teddy bears, Bernal said.

britney.barnes@latimes.com

Twitter: @britneyjbarnes

If You Go

What: South Coast Invitational Marching Band Tournament

When: 5 p.m. Wednesday

Where: Jim Scott Stadium, 2323 Placentia Ave., Costa Mesa

Cost: $10 admission, with all of the money going directly to the band