Bianca Buono of ABC6 in Providence, Rhode Island, tweeted a photo of the note:
In the note, Hernandez wrote he "indirectly" told Jenkins-Hernandez his death was coming.
Hernandez was found hanging in his prison cell early on the morning of April 19 and was pronounced dead shortly thereafter. A medical examiner ruled his death a suicide.
Per WCVB, Hernandez left three suicide notes, one of which was written to Jenkins-Hernandez.
The former New England Patriots tight end was serving a life sentence in prison without the possibility of parole for the 2013 murder of semi-professional football player Odin Lloyd.
Days before his death, Hernandez was found not guilty in the 2012 shooting deaths of Daniel de Abreu and Safiro Furtado.
Following his death, Hernandez's attorneys moved to have his murder conviction vacated due to a Massachusetts law that allows abatement if a person dies before their appeals process is completed, according to Antonio Planas, Chris Villani and Laurel J. Sweet of the Boston Herald.
In the letter to Jenkins-Hernandez, Hernandez told her, "You're rich."
Per TMZ Sports, Lloyd's mother's attorney, Douglas Sheff, believes the Patriots may be forced to pay $6 million of Hernandez's contract if his conviction is overturned.
Hernandez signed a seven-year contract worth over $39.5 million with the Pats in 2012 before being released in 2013.