US investigators have found evidence of sexual abuse of children at Horace Mann School in New York City between the 1960s and 1990s.

The Bronx District Attorney's office said on Friday that a pattern of sexual abuse of students by school employees was uncovered. However, complaints cannot be prosecuted because the crimes were committed a long time ago.

The investigation into the allegations of abuse came after New York Times Magazine published an article that accused some former instructors at the school in the Bronx of abusing and raping students.

Police and investigators interviewed over 20 former students of the school who said that they had suffered sexual abuse at the school.

According to a statement by the Bronx District Attorney, Robert Johnson, at least 12 former school employees were accused of being involved in the abuse.

The statement said that the interview conducted by the Bronx District Attorney's office and the New York City Police Department (NYPD) disclosed “a systemic pattern of alleged abuse beyond what was outlined in the original New York Times Magazine article.”

    “The reported abuse ranges from what may be characterized as inappropriate behavior to child endangerment, actual instances of sexual contact, sexual intercourse and criminal sexual acts,” Johnson added.

He pointed out that the majority of the sexual abuses are reported to have occurred in the 1970s and some school authorities were aware of the abuse, but they did not inform the police.

Earlier this year, according to Local media reports, Horace Mann School paid hundreds of thousands of dollars in settlement to most members of a group of 32 students who said they had been sexually molested.

Under the current New York state law, victims of child sex abuse in most cases are able to file complaints only until they are 23 years old.