During testimony this week in U.S. District Court in Camden, a South Jersey police officer testified that retired Bordentown Police Chief Frank Nucera Jr. routinely used racial slurs and said black people should be shot.

Sgt. Nathan Roohr, a K-9 officer in the Burlington County department, testified Monday that, during an arrest in 2016, Nucera grabbed the head of an African American suspect “like a basketball” and slammed it into a metal door jam. “[It] made a loud thud,” Roohr said. “I immediately knew it was wrong. I knew I had an obligation to report it,” he added. “This was an obvious excessive force.”

The suspect, 18-year-old Timothy Stroye, was handcuffed at the time. Stroye and his 16-year-old girlfriend were accused of sneaking into a hotel and using the pool.

Nucera, who retired abruptly in 2017, has been charged with hate-crime assault, as well as civil rights violations and lying to the FBI. Prosecutors maintain he had a “significant history” of making racial remarks. Roohr and other officers provided dozens of tapes of their former commanding officer spewing racist threats: In one, Nucera can be heard saying: “It’s gonna get to the point where I could shoot one of these [N-words].”

After tires on a squad car were slashed, Nucera reportedly claimed, “These [N-word] are like ISIS, they have no value. They should line them all up and mow ’em down. I’d like to be on the firing line, I could do it.”

Roohr also said Nucera directed K-9 officers to use police dogs to intimidate black people. “Let these [expletives] see him. Let ’em see him. I don’t care,” Nucera can be heard saying in a recording.

Nucera’s attorney, however, maintains the accusations were drummed up by officers dissatisfied with his disciplinary and overtime policies.

When charges were originally filed, U.S. Attorney William Fitzpatrick said the accusations against Nucera painted a picture of “intense racial animosity toward African Americans.”

“The conduct alleged is a shocking breach of the duty of every police officer to provide equal justice under the law and never to mistreat a person in custody,” Fitzpatrick added. “As a result, the former chief of police is now a charged federal criminal defendant.”

If convicted, Nucera could face up to 20 years in prison and forfeit his $8,800 a month pension.