Update: On Oct. 11, the trial of Frank Nucera Jr., a former police chief, ended without a verdict on charges that he committed a hate crime and deprived a suspect of his rights during a 2016 arrest. Mr. Nucera was convicted of making false statements to the F.B.I. The United States attorney in New Jersey said he would be retried on the outstanding counts.

A former police chief in New Jersey who is on trial on a federal hate-crime charge after he allegedly slammed a black teenager’s head into a doorjamb, once called President Trump “the last hope for white people,” according to a recording recently played for jurors.

In the 2016 recording, which federal officials shared with The New York Times, Frank Nucera Jr., the former chief, can be heard saying that Mr. Trump was the last hope because “Hillary will give it to all the minorities to get a vote. That’s the truth! I’m telling you.”

The Trump comment was surreptitiously recorded by a Police Department colleague just months before the 2016 presidential election .

The recording was played in court last week by prosecutors in an effort to show that the alleged attack in September 2016 by the former chief on a guest — an 18-year-old black man — at a Ramada Hotel in Bordentown, N.J., was motivated by Mr. Nucera’s “intense racial animus.”