A Hollis/Brookline Middle School teacher allegedly led a stunning double life: instructing students in English while robbing banks and gambling on the side.

Unarmed and slipping tellers hand-written demands on envelopes, Gail Rasmussen last month robbed two banks in Massachusetts and one in Connecticut, walking away with as much as $3,000, police charge.

After robbing the bank in Plainfield, Conn., the 49-year-old teacher was spotted at nearby Mohegan Sun Casino, police said. As part of her bail condition, Rasmussen was ordered by a judge to undergo evaluation by Gamblers’ Anonymous, according to published reports.

News of Rasmussen’s arrest last week came as a surprise in Hollis, where Rasmussen teaches seventh grade, and in Brookline, where she lives.

“She seemed actually a little bit shy – a little more reserved than some of the other teachers. But she was serious, very competent, really knew her stuff. I thought she seemed pretty level-headed,” said Hollis resident Kim Bolling, whose children have been taught by Rasmussen.

Rasmussen turned herself in to Concord, Mass., police Dec. 30 for allegedly robbing a bank there Dec. 20, while police in Tyngsborough, Mass., on Thursday were obtaining a warrant for her arrest for an alleged bank robbery there Dec. 16.

Rasmussen will probably face similar charges in Plainfield for robbing Eastern Federal Savings Bank on Dec. 19 and walking away with $1,800, according to the New Hampshire Union Leader.

Not long after the robbery, Plainfield police learned that a woman who matched Rasmussen’s description was at the nearby casino, the Union Leader reported.

The description given by the three banks was that of a short, middle-aged woman, wearing a heavy winter coat and scarf, police said. It is estimated that Rasmussen pocketed at least $3,000, police told The Boston Globe.

Rasmussen was put on indefinite paid administrative leave as of Wednesday, according to Hollis/Brookline Cooperative School District Superintendent Susan Hodgdon. Under state statute, the school district would need just cause to move forward with any kind of permanent removal, she said.

Rasmussen, of 17 Winterberry Road allegedly robbed the Tyngsborough bank first.

On Dec. 16, she walked into Washington Savings Bank, showed a note and walked away with money, Tyngsborough Police Chief William Mulligan said Thursday. She called in sick to work that day, police said.

Four days later, Rasmussen walked into TD Bank in Concord, handed a bank teller a note and left with $1,200, Concord, Mass., police said.

The note, according to a police report obtained by The Globe, read: “Please give me $2,000 all large, no dye pack.” When the teller paused, Rasmussen told her to “hurry up,’’ the report said. The teller gave her $1,200, including “bait’’ currency with known serial numbers, the report said.

After the robbery, the bank manager saw Rasmussen get into a gray Honda and speed away, the report said.

Police in Tyngsborough and Concord noticed similarities in their robberies and started working together to catch Rasmussen, officials from both departments said.

Brookline police assisted the two departments in searching Rasmussen’s home Tuesday.

After turning herself in to Concord police, Rasmussen was arraigned and released on $500 bail, Concord police Sgt. Brian Goldman said. She was ordered to seek help through Gamblers Anonymous and to live with her mother in Winchendon, Mass., until her next court date on Feb. 23, according to the Union Leader.

Rasmussen first started working for the school district in 1999 as a paraprofessional, according to Hodgdon. She then went back to college and worked for Wilton-Lyndeborough Cooperative School District before returning to Hollis/Brookline in 2005 to fill in as a continuing substitute for a teacher on maternity leave. Rasmussen was hired on a permanent basis the following year.

Hodgdon said she sent out an e-mail to parents, students and staff Thursday alerting them to the situation. Hodgdon said the school would draw upon existing staff to cover the vacancy.

“It’s an unfortunate set of circumstances,” Hodgdon said. “Certainly, this was all in the personal side of Gail Rasmussen’s life and did not show itself in the classroom at all.” Hodgdon declined to comment on Rasmussen’s effectiveness as a teacher or whether she had received positive evaluations in the past.

Bolling, of Hollis, has two childen, one of whom was in Rasmussen’s class a few years ago and one who is in Rasmussen’s class this year. Bolling said her children liked Rasmussen and described her as “a little strict.” Bolling met the teacher a few times at open houses and school functions.

“We didn’t believe it. She was one of the last people I would believe would do that,” Bolling said.

Brookline police Sgt. Michael Kurland said Rasmussen posed no threat to her students.

Rasmussen’s arrest marks the second time in three months that a Hollis/Brookline Cooperative School District teacher has been charged with a crime.

Christopher Cieto, who resigned as a high school English teacher shortly before being arrested in September, is charged with sending obscene e-mails and stalking the mother of one of his students.

Staff writers Michael Brindley, Joseph G. Cote and David Brooks contributed to this report. Albert McKeon can be reached at 594-5832 or amckeon@nashuatelegraph.com.