SANFORD, Fla. -- Authorities say George Zimmerman threatened a private investigator working for a documentary filmmaker.

Court records show Zimmerman was issued a summons for a May 30 arraignment on a charge of misdemeanour stalking.

A sheriff's report says the investigator contacted Zimmerman in September on behalf of Michael Gasparro, who is making a documentary on Trayvon Martin. The series is being produced by rapper Jay-Z.

Court records show the private investigator received 55 phone calls, 67 text messages, 36 voicemails and 27 emails from Zimmerman in December.

The records don't list an attorney for Zimmerman.

Zimmerman identifies himself as Hispanic. The former neighbourhood watch volunteer fatally shot the 17-year-old Martin in 2012 in the central Florida city of Sanford. He was acquitted of all charges. Martin was black.