The convicted mastermind of a jihadist plot to blow up jet-fuel supply tanks and a pipeline at New York City’s John F. Kennedy International Airport is suspected of having conspired to murder his “Jewish attorney,” among others, while in jail, according to a letter unsealed in Brooklyn federal court.

Russell Defreitas, 68, was sentenced to life in prison in 2010 after being convicted of a plot to blow up fuel pipelines at JFK International Airport. However, according to newly released court documents, Defreitas also planned to kill key witnesses and his “Jewish attorney,” before the trial against him began, prosecutors wrote in newly unsealed documents.

He allegedly asked his fellow inmates to help him carry out several murders, including that of the attorney, Mildred Whalen, “because she is the reason his first attorney was removed from the case.” 

Whalen told CNN that she thought the claims were “ridiculous” and that she never felt threatened by Defreitas.

Defreitas was arrested in 2007 after an undercover policeman was recruited to take part in the JFK plot, along with Kareem Ibrahim, Abdel Nur and Abdul Kadir, all of whom were extradited to the U.S. and convicted of planning the attack.

The complaint filed in court indicting the four men included a recording of a statement made by Defreitas to the government’s informant in which he said, “Anytime you hit Kennedy, it is the most hurtful thing to the United States. To hit John F. Kennedy, wow… They love John F. Kennedy like he’s the man… If you hit that, the whole country will be in mourning. It’s like you can kill the man twice.”