Investigators work around wreckage of Home Depot pickup truck that alleged terror suspect Sayfullo Saipov used to mow down people on a bike path in New York City, Nov. 1, 2017. (Photo: R. Taylor / VOA)
FILE - Investigators work around the wreckage of a pickup truck that alleged terror suspect Sayfullo Saipov used to mow down people on a bike path in New York City, Nov. 1, 2017.

NEW YORK - A man charged with killing eight people by driving a truck down a lower Manhattan bike path in October 2017 recently threatened to decapitate an officer at the jail that has housed him since his arrest, U.S. prosecutors said.

In a Tuesday night court filing, the Department of Justice said Sayfullo Saipov made the threat on Dec. 18, after the officer's supervisor told Saipov to stop obstructing a security camera in his cell at the Metropolitan Correctional Center in Manhattan.

Prosecutors said they want to introduce the incident as "proof of future dangerousness" during the penalty phase of Saipov's case, if he is convicted at his April 20 trial.

FILE - Sayfullo Saipov, the suspect in the New York City truck attack, is seen in this handout photo released Nov. 1, 2017, by St. Charles County Department of Corrections.

Saipov, a 32-year-old Uzbek national, has pleaded not guilty to charges including eight counts of murder, 18 counts of attempted murder and providing material support to Islamic State militants. He could get the death penalty if convicted.

Federal public defenders representing Saipov did not respond to requests for comment.

In a Wednesday court filing, the public defenders said they may try to exclude anything Saipov said while in custody at the jail that was involuntary or not responsive to questions, citing his constitutional right against self-incrimination.

According to prosecutors, Saipov first threatened to kill the officer on Dec. 17, confronting him over his alleged practice of frequently waking him at night by slamming a door.

Still angry the next day, Saipov told the supervisor he would keep blocking the security camera until the officer's head was cut off, and called the officer an animal, prosecutors said.

Saipov later told the jail's disciplinary committee he had told the officer that if he dared to open his cell, in two minutes "other guys will be picking up your dead body," and that he wanted to "cut this animal head off," prosecutors said.

The government also wants permission to introduce other evidence during Saipov's trial and penalty phase. It said this included terrorist propaganda materials, photographs from the Oct. 31, 2017, attack, and statements Saipov made in court that showed his support for Islamic State and jihad and questioned the court's authority.

Metropolitan Correctional Center 

Other recent inmates at the Metropolitan Correctional Center have included the late financier and registered sex offender Jeffrey Epstein, convicted Mexican drug lord Joaquin "El Chapo" Guzman and Cesar Sayoc, who mailed pipe bombs to prominent Democrats.

Michael Avenatti, the lawyer who represented adult film actress Stormy Daniels in lawsuits against U.S. President Donald Trump, is now housed at the correctional center awaiting two criminal trials, following his Feb. 14 conviction for trying to extort Nike Inc.