The career criminal charged with murder in a subway fire that killed an MTA motorman was perp-walked past furious transit union leaders Friday on his way to court.

“Rot in hell,” Transit Union Workers officials shouted at Nathaniel Avinger as he was led out of the 28th Precinct stationhouse in handcuffs.

“Murderer,” another yelled. “Life in prison.”

Robert Kelley, a TWU Local 100 vice president, told The Post, “I can’t begin to tell you how upset my stomach is. This murderer took a family man from his family, just for coming to work. I hope he rots in hell.”

Avinger, 50, is charged in the March 27 arson fire on a Harlem No. 2 train that killed motorman Garrett Goble and injured 16 others.

Avinger was questioned shortly after the incident but released — then arrested Wednesday for allegedly groping a female transit worker and charged in the arson case.

Goble was a married father of a 10-year-old son and a 5-month-old baby.

“The emotions are still raw,” said Eric Loegel, another TWU VP. “There is still anger about what happened. So, probably a mixture of feeling relieved that they caught him and he’s off the streets, but also angry about what this man did.”