New York ( CNN ) -- The convicted architect of a 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 one of his attorneys , among others , while in jail , according to a letter unsealed in Brooklyn federal court . Russell Defreitas allegedly asked his fellow prisoners to help him carry out several murders , according to a March 2010 letter from prosecutors to Defreitas ' attorneys , which was released Tuesday . He allegedly told a fellow inmate that he wanted his attorney , Mildred Whalen , whom he described as `` Jewish , '' dead `` 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 . The letter says Defreitas also threatened to kill a witness named `` Rutherford , '' as well as an unnamed prosecutor . According to the inmate , who is identified in the letter as `` W1 , '' Defreitas said that his co-defendant in the JFK plot , Abdel Nur , told him that the prosecutor `` had to go . '' Defreitas asked the inmate to contact his wife in Guyana and to deliver these messages to her , in exchange for a `` promotion in Muslim ranks '' and access to Defreitas ' `` contacts , '' the letter says . Another target of Defreitas ' alleged prison plot included Steve Francis , an informant who secretly taped Defreitas and his JFK plot conspirators . He allegedly discussed plans to kill Francis with a second prisoner , identified in the letter as `` W2 . '' Defreitas told the prisoner that he thought Francis had taped around 150 hours of recordings regarding the JFK plot , but had recently found out that there were more than 300 hours , the letter detailed . He allegedly told the prisoner that `` the only way to beat the case now was to have Francis killed , '' according to the letter . The prisoner apparently would have been paid by Defreitas ' associate , Harry Baptiste , in exchange for murdering Francis . Defreitas ' former attorney , Whalen , said the allegations were unsubstantiated , which is why they were not admitted during trial . Defreitas , a U.S. citizen from Guyana , was sentenced to life in prison last year for masterminding the airport plot . CNN 's Jonathan Noah contributed to this report .
Russell Defreitas allegedly asked his fellow prisoners to help him carry out several murders . His attorney said she thought the claims were `` ridiculous '' and that she never felt threatened . Defreitas was sentenced to life in prison last year for masterminding the airport plot .