A teacher from Connecticut has been accused of carrying on inappropriate relationships with two teenage students - and sexually assaulting one in the high school where she works.

Allison J. Marchese, 37, from Madison turned herself into police on charges of second-degree sexual assault and impairing the morals of a minor, police and school officials said.

Police say they discovered inappropriate text messages - as well as sexy selfies of herself wearing only a thong and a bra.

Mrs Marchese is now on paid leaving pending the outcome of an internal investigation.

Harmless? This 'selfie' of Marchese 'dressed in only thong style underwear with her breast covered and her midriff exposed' was sent to a student

After investigating for almost five weeks, police were able to get all of the information they needed; including talking to people at the Daniel Hand High School, reviewing phone records, and locating some inappropriate pictures that were exchanged between the teacher and the student.​

Pending: Marchese, 37, who has worked at the school district for 12 years and is a mother of two children, is on paid leave pending the outcome of an internal investigation

There were winking, smiling emoticons, flirtations, sexual hints and a 'selfie' of Mrs Marchese 'dressed in only thong style underwear with her breast covered and her midriff exposed,' according to police.

The indiscretion was taking place directly under the nose of her husband, Robert Marchese, 39, who not only taught at the same school but also in the same English department.

Court records show that she struck up relationships with two teenage boys at the school and it wasn't long before rumors started circulating in classrooms.

In the arrest warrant affidavit, a 17-year-old student told police he received a selfie of Marchese scantily dressed.

In her defense, the affidavit says Mrs Marchese said she sent the photo to her husband.

In one instance, Mrs Marchese messaged the 17-year-old through Instagram to come to her classroom. The teen excused himself from a different class by pretending he needed the bathroom and headed to Room 347 where Mrs Marchese was allegedly waiting.

'Once in the room, they got into each other's personal space and started to 'hook up' which he described as kissing each other and she then started touching him 'downtown,'' the affidavit said.

Fearing it was 'not safe,' Marchese 'locked the classroom door and closed the blinds.' She then performed a sex act on him, the affidavit said.

After the summer break ended in September 2014, the student wanted to cool the relationship off but Mrs Maechese was addicted as did not want their encounters to stop.

She sent him a confusing Instagram message that said, 'I know when to stop, I know when to move on, but I know is different from I can,' the affidavit said.

Desperate to put an end to the encounters, the teenager then came up with a plan to blackmail Marchese, telling her that he would stay silent about their relationship if she gave him $200.

In response, the teacher let him know that her father had 'Mafia ties' who would make sure he 'would never play football again,' if he told anyone.

The student finally gave in and reported the allegations to staff at the school. The police were contacted and the English teacher was arrested on January 7 WTNH-TV reports.

Media message: At one point Marchese messaged the teen through Instagram to come to her classroom. The teen told the teacher whose class he was in at the time he had to use the bathroom and went to see Marchese

When police went to the school to look into the allegations they discovered that there were others with whom the teacher had behaved inappropriately with.

Madison police investigators also interviewed 15-year-old student who claimed that he too had a relationship with Mrs Marchese, that began when he was 14. Like the 17-year-old, much of the communication took place through Instagram.

The student told investigators that Mrs Marchese had texted him to say that she could not concentrate on teaching her own class because he he was so attractive.

The younger teen said Marchese messaged him 'nonstop' the first week of summer vacation, including long messages expressing her feelings and trying to make him feel badly for not responding.​

The English teacher at Daniel Hand High School, Marchese is now on paid leave pending the outcome of an internal investigation.

Playing with fire: Madison police began investigating Marchese in early January after the 17-year-old went to the principal

Silent: Nobody has been at home to speak to the press in recent days to discuss the allegations

'I find the alleged conduct of this teacher vile and disgusting,' Superintendent of Schools Thomas R. Scarice said. 'The bond of trust between a professional educator and a student is fragile and precious. The violation of this bond is nothing less than reprehensible.'

Broken down: Robert Marchese, 39, who also teaches English at Daniel Hand has now filed for divorce against his wife. He is looking after their two children

Education officials have said they will take 'the 'most aggressive actions possible to see to it that any individual who abuses theirs bond is removed from the profession and brought to justice.'

Under state law, second-degree sexual assault is a felony that carries a sentence of up to 10 years in prison and a fine of up to $10,000. If the victim is under 16 years of age, the maximum sentence is 20 years in prison and a fine of up to $20,000.

Mrs Marchese had worked in the school district for 12 years and was a well regarded teacher.

The school has put in place support services to help students who may need some support.

Mrs Marchese's husband, Rob, 39, also teaches at the school.

During an interview with Madison police in January, Robert Marchese told investigators that his wife had recently become obsessed with 'social media and working out.'

He said his wife told him she was having an 'inappropriate relationship' with the 15-year-old, communicating with him in 'sexually explicit ways,' and that she 'admitted having oral sex' with the 17-year-old, the affidavit said.

He also turned over tape recordings of a conversation he had with his wife in which she admitted those things, according to the affidavit.