A panel of U.S. Court of Appeals for the Second Circuit judges questioned a Brooklyn federal judge's decision to sentence a man accused of attempted murder and planning to join ISIS to 17 years in prison in a decision Friday, which remanded the case for resentencing in the Eastern District of New York.

Federal guidelines recommended that Fareed Mumuni, who pleaded guilty to attempting to murder an FBI agent with a kitchen knife and conspiring to support ISIS, be sentenced to 85 years in prison. While judges have the flexibility to issue sentences that vary from federal guidelines, Judge José Cabranes of the U.S. Court of Appeals for the Second Circuit wrote in his majority opinion that the 17-year sentence from U.S. District Judge Margo Brodie of the Eastern District of New York was unreasonable.

"The District Court's clearly erroneous findings and legal error resulted in its improper discounting of the seriousness of Mumuni's offense conduct," Cabranes wrote. "Mumuni's attack was not a spontaneous assault of a federal officer amid a heated altercation. Nor was it an act of self‐defense. Mumuni's violent attack against Agent Coughlin was indisputably a premeditated, willful, and deliberate attempt to murder a federal officer in the name of ISIS."

Brodie should not have second-guessed whether Mumuni actually intended to kill the FBI agent after accepting his guilty plea, Cabranes wrote. According to a transcript included in the Second Circuit decision, Mumuni told Brodie he did attack the agent knowing that he could kill him.

But at Mumuni's sentencing, Brodie said it wasn't clear whether he intended to kill the agent and wondered whether he produced the knife while expecting to be killed by the FBI agents, according to a transcript excerpt. Such speculation was not supported by the law or the record, Cabranes found.

The FBI agent happened to be wearing an armored vest at the time of the attack, inside Mumuni's family home, but vests are meant to protect people from bullets, not stabbing attacks, Cabranes wrote. The knife went through the agent's vest and damaged a metal magazine carrier inside, investigators found.

Brodie considered several mitigating factors, including Mumuni's lack of a criminal record, his good behavior while awaiting trial, letters of support from family and friends and the fact that he was 21 years old on the day of his arrest in 2015. Cabranes did not disagree that those factors existed, but he found that such a major departure from federal guidelines must be justified by a more substantial mitigating factor.

Cabranes described the 17-year sentence as "shockingly low," and in a partial dissent, Judge Peter Hall of the U.S. Court of Appeals for the Second Circuit voted to remand but said he didn't believe the sentence was shockingly low.

Hall said he hoped to learn more about why Brodie second-guessed Mumuni's intent to kill the FBI agent, but he emphasized that Mumuni's youth and good behavior are important factors that informed the 17-year sentence.

"It should not be out of the realm of possibility for the District Court to determine, after fully analyzing all the applicable factors including those for which we have ordered remand and Mumuni's behaviors and course of conduct subsequent to his April 2018 sentencing, that the appropriate punishment to be imposed is a term of incarceration similar to (the 17-year term) imposed twenty months ago," Hall wrote.

A spokesman for the U.S. Attorney's Office for the Eastern District of New York declined to comment Friday. Mumuni's lawyers, Kenneth Montgomery and Anthony Ricco, did not immediately respond to requests for comment.