The San Carlos School District in San Carlos, Calif. retaliated against the parents of a child with special needs by making allegations that resulted in a sheriff’s deputy visiting their house, a letter sent to the family by the U.S. Department of Education concludes.

The March 6 letter was sent in response to a complaint the parents submitted last year after a district official contacted the San Mateo County Sheriff’s Office in October 2012 and claimed the child’s father secretly taped a meeting with district educators. The name of the family was blacked out from a copy of the letter obtained by The Daily News.

Although the parents weren’t charged with any crimes, the allegation of criminal behavior, the deputy’s visit and the veiled possibility of arrest and prosecution “are all sufficiently adverse since one or all of them would be reasonably likely to deter a parent from advocating on behalf of their child,” the federal agency’s letter states.

According to facts outlined in the letter following an investigation by the agency’s Office for Civil Rights, the student was in the second grade during the 2012-2013 school year and received special education services because of a health impairment and a speech or language impairment. The parents were “proactive” in seeking special services for their child, sometimes “questioning determinations made by the district.”

On Sept. 27, 2012, after an individualized education program meeting between the district and family to discuss the student’s needs, a teacher informed the school principal — who had not attended — that she believed the student’s father had recorded the meeting. The father wanted to record a meeting before that one and was told the district did not allow recordings without 24 hours notice. He had recorded an earlier meeting but was not told then about the district’s policy.

The principal informed the district’s director of student services about the suspected recording, according to the federal agency’s letter. On Oct. 3, the student displayed “significant behavioral issues” at school and the parents sent an email to the principal seeking a consultation with the school psychologist. Later that same day, the director of student services, who is not named, made a report to the Sheriff’s Office, according to the letter.

On Oct. 13, a deputy went to the family’s home, was told that no one recorded the meeting and closed the investigation, stating in a report that there was “no proof a crime was committed.”

The timing of the district’s actions, relative to the parents’ advocacy, “warrants an inference that the adverse action was caused by the protected activity,” the federal agency’s letter states.

During the Office for Civil Rights probe, the director of student services told investigators that she spoke to the district’s lawyer, schools Superintendent Craig Baker and the school board about her intention to call the Sheriff’s Office to report the alleged illegal recording. But “she never met or spoke with the complainants about the allegation or attempted to obtain their version of events,” the letter states.

Calling law enforcement “undoubtedly has a deterrent and chilling effect on parents and their willingness to actively participate in their own children’s education and advocate on their behalf,” the letter adds. For that reason, a call should be made only when the harm is sufficient enough to warrant such involvement.

The student services director told investigators that the school district’s attorney advised her state law says it’s illegal to record conversations without the prior knowledge and consent of everyone. But state law does not apply to IEP meetings, the federal agency’s letter notes.

To resolve the matter, the district signed off on an agreement that, among other things, requires it to distribute a memo to staff warning against illegal retaliation against families of students in special education and offering to provide training. The agreement, signed by Baker, states that the district does not admit any violation of the law.

In a written statement to The Daily News, school board President Adam Rak said the district is “committed to fair, non-retaliatory treatment of all students and families and it respectfully disagrees with the characterization of facts and conclusions” in the Office for Civil Rights report.