A Staten Island chiropractor was arrested and charged with aggravated harassment Monday after a vulgar letter allegedly penned by her appeared in the home mailbox of a cop from the 120 precinct, sources said.

Danielle Serini, 38, who had been arrested in February for harassing a school crossing guard, allegedly had the letter sent to the home of the officer in charge of crossing guards in her precinct, according to law enforcement sources.

The letter allegedly appeared in the officer’s home mailbox Monday morning and included foul language, according to sources.

The chiropractor was being held at the 120 Precinct Station house in St. George Monday night.