The 21-year-old undocumented immigrant accused of sexually assaulting and killing a 92-year-old woman while she walked near her home pleaded not guilty in a New York courtroom on Thursday.

Authorities allege Reeaz Khan assaulted Maria Fuertes in the early morning hours of Jan.6

Wearing a brown jacket, Khan was brought into the courtoom with his hands cuffed behind his back.

Prosecutors asked the judge for an additional two weeks before proceeding. A new court date has been scheduled for Feb. 24.

Surveillance footage shows Khan following Fuertes and then knocking her to the ground near some parked cars, District Attorney Melinda Katz said. The video also shows Khan sexually assaulting Fuertes and fleeing from the scene, authorities said.

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"This was a senseless, brutal act of violence," Katz said. "The victim was found with her clothes pulled above her waist, and near death."

A passerby called 911 and the nonagenarian was taken to a nearby hospital, where she died of her injuries.

Khan's brother saw the grainy footage and turned his brother in. Khan, a day laborer, lives within a mile of the murder scene. He was charged with second-degree murder and first-degree sexual assault. Khan purportedly first told investigators that Fuertes had fallen and he had tried to help her up. During questioning, that excuse quickly crumbled and Khan admitted to having sexually assaulted Fuertes.

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The case has become a flashpoint between the Trump administration and New York City leaders over its sanctuary policies.

On Monday, Immigration and Customs Enforcement demanded the city hand over information on Khan. ICE claims it issued a detainer request for Khan, who is from Guyana, after authorities arrested him during an earlier incident where he's accused of assaulting his father with a broken coffee cup.

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The NYPD denied receiving a detainer, a request by ICE to hold undocumented immigrants who have been charged or convicted of crimes for two days after their release so that immigration officials can pick them up. ICE released a copy of the fax form they sent to New York authorities dated Nov. 27.

Less than two months after his release, Khan allegedly killed Fuertes.

"A phone call, one simple phone call and Maria Fuertes could be alive today," ICE Director Matthew Albence told reporters.

During his State of the Union address this week, Trump claimed that New York's laws led to Fuertes' rape and murder.

"If the city had honored ICE's detainer request, his victim would be alive today," Trump said.

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That assessment didn't sit well with some and led to more than 120 groups signing a letter in support of the city's approach to detainer policies. The letter, sent to New York City Democratic Mayor Bill de Blasio, strongly pushed back on Trump's assessment of the situation.

This isn't the first time Trump has slammed sanctuary cities. He frequently targets San Francisco, Los Angeles and Chicago and claims the cities have become a hideout for criminals who jeopardize public safety.

Fox News' Jennifer Oliver contributed to this report.