CONCORD — A former Hooksett middle school music teacher pleaded guilty Tuesday in Merrimack County Superior Court to four charges of aggravated felonious sexual assault and was sentenced to 7 1/2 to 16 years in prison, although he could be released in six years if he completes a sexual offender program.

Andrew Lalos, 35, was accused of sexually assaulting the girl when she was 16 and 17 years old. She had been a student of his at Cawley Middle School and returned in 2005 as an intern while in high school, which is when police said the sexual assaults occurred on school grounds and at the residence of the married father of two.

Lalos, who had been free on bail, was taken into custody immediately following the sentence, which cannot be appealed.

The capped plea and sentence agreement calls for concurrent sentences of 7 1/2 to 16 years on two pleas. Concurrent sentences of 10 to 20 years on the remaining two charges are suspended, but would be consecutive to the 7 1/2- to 16-year sentences if imposed.

Assistant Merrimack County Attorney Wayne Coull said the plea agreement called for Lalos to complete the prison's sexual offender program and still serve the minimum sentence of 7 1/2 years.

But Judge Richard McNamara granted a defense request to reduce the minimum sentence by 18 months if Lalos completes the sexual offender program.

“I did not think that was appropriate,” Coull said.

Lalos was arrested on the assault charges in June 2011, a year after the Hooksett Kiwanis club named him the Hooksett Educator of the Year. At the time of his arrest, he was scheduled to conduct a weeklong band camp in July.

Lalos had also volunteered and worked as a music instructor at other schools in the area, including the Manchester Community Music School.

Police said the victim, now in her 20s, came forward last year.

The state's Internet Crimes Against Children Task Force said Lalos developed a relationship with the girl online before it escalated into one of a sexual nature.

He was charged under a provision in the state's rape law that bans a person with “authority” to “coerce the victim to submit” to sex, which is RSA 632-A:2 (k). That provision only applies if the victim is less than 18 years old. At the time of the assaults, the girl was under 18 and Lalos was her mentor.