A jury already convicted five correction officers on Tuesday of assault in the brutal attack on inmate Jahmal Lightfoot.
Captain Gerald Vaughn opted for a bench trial in the case and was found guilty by Justice Steven Barrett.
Vaughn was found guilty of assault and official misconduct following the 12-week trial and could face 15 years in prison when he is sentenced on Sept. 6, according to the Bronx District Attorney's Office.
Correction Officers Harmon Frierson and Dwayne Maynard, who opted for a bench trial as well, were also convicted of official misconduct, and they will face up to one year in jail when sentenced on Sept. 6, the Bronx DA's Office said.
Bronx District Attorney Darcel Clark, who has made improving Rikers one of her top priorities, reiterated in a statement that inmates deserve to be treated like human beings.
"These convictions, along with those of the assistant security chief of DOC and four officers earlier this week, close a chapter in Rikers Island’s sad, brutal history," she said.
Elias Husamudeen, who recently replaced Norman Seabrook as president of the Correction Officers' Benevolent Association following Seabrook's arrest for fraud, described the ruling in a statement as "outrageous" and was adamant that the union would not let its members' lives be ruined to satisfy a political agenda.
"When the legal system in this country continues to persecute correction officers for doing their job, while defending violent criminals, everyone should be outraged," he said.
DOC Commissioner Joseph Ponte again stressed that the vast majority of correction officers do their jobs well and said the agency would work to build a culture where both inmates and officers feel safe.
"Everyone in our custody deserves to be treated in a just and humane manner," he said in a statement.