CHICAGO (CBS) — A former teacher at a West Side Christian school is being held on $1.5 million bond, on charges that she sexually assaulted four students for a period of years.

Elisa Martinelli, 34, of the 1500 block of South Raymond Drive Naperville, was charged with four counts of criminal sexual assault. Her bond was set at a hearing Tuesday.

Her brother, Nelson Quintana Jr., 27, who also worked at the school, is charged with one count of misdemeanor criminal sexual abuse, police said.

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Martinelli is assaulting three girls and a boy several years ago while they were students and she was a teacher at the Dayspring Christian Academy at 5133 W. Fullerton Ave.

The alleged crimes occurred in the late 1990s but were reported to police in April, according to police.

In court Tuesday, prosecutors said Martinelli first abused a 15-year-old girl she had taught in seventh and eighth grade, the Chicago Sun-Times reported. The abuse lasted from 1998 to 2001, and began with sexual stories but later became physical molestation, the newspaper reported.

In the second incident in 2003, Martinelli allegedly sexually abused a 15-year-old girl and her brother, with whom she had sex for a year, the newspaper reported.

Finally, Martinelli allegedly participated in mutual sex acts with a 14-year-old girl whom she had taught in sixth and eighth grades, until the girl’s family left town in 2007, the Sun-Times reported.

Prosecutors say she Martinelli plied the students with alcohol.

Martinelli’s father, Nelson Quintana Sr., is pastor of the neighboring Dayspring Church.

Dayspring Academy is a private Baptist school with students from pre-kindergarten through grade 12.

The Sun-Times Media Wire contributed to this report.