(CNN) New York terror suspect Sayfullo Saipov was surveilled for three years, right up until the eve of the deadly attack he stands accused of carrying out. Now, he wants access to what the government knows, according to a motion filed Monday in the Southern District of New York.
"The government revealed it had been surveilling Mr. Saipov and two of his associates for years, recording his conversations with them to gather information about his personal contacts, professional experiences, finances, and potential exposure to ISIS propaganda, violent jihadism, and Islamic extremism," Saipov's attorney Andrew Dalak argued in the heavily redacted filing.
Dalak wrote the government must disclose details of the surveillance and any materials pertaining to his client's alleged connection to ISIS, so the legal team can mount a defense.
Saipov is facing the death penalty after being accused of running down pedestrians with a truck on New York's West Side bike path on Halloween 2017, killing eight people. He has been charged with 28 counts, including eight counts of murder, 18 counts of attempted murder, and other terrorism charges. The attack was the deadliest terror attack in New York since 9/11.
"The government cannot prosecute someone while keeping secret the original sources of its evidence and information it relied upon in the course of its investigation," Dalack wrote.
The government has argued the surveillance was not used to derive any evidence it plans to bring at trial, and that therefore it is not obliged to include the surveillance in discovery.
Lawyers for Saipov argued Monday that their client is entitled to know why and how the government surveilled him, whether that surveillance has contributed to the evidence against him, and whether that evidence was legally obtained.
Dalack said the details of the surveillance were particularly important given that his client may face the death penalty.
"Indeed, if [REDACTED], or any of Mr. Saipov's other friends suspected of sympathies to ISIS and / or Islamic extremism [REDACTED] influenced Mr. Saipov's 'radicalization' or spurred him to action," Dalack wrote, "the jury could find that they share moral culpability for the events of October 31, 2017, and spare Mr. Saipov's life."
Many of the details about the government's surveillance were redacted from Monday's court filings. The surveillance came to light in a December letter to the court filed by Saipov's legal team, describing "numerous audio recordings of conversations between Mr. Saipov and various targets of FBI Surveillance," produced by the prosecution. The conversations were largely in Uzbek, the letter said, and one had been recorded on October 30, 2017, the day before the attack.
Last week, Judge Vernon S. Broderick ruled in favor of a defense motion to postpone the trial. It is now scheduled to begin on April 13, 2020.