A 28-year-old man is under arrest for the caught-on-video fatal beating of a senior citizen in Brooklyn in September, cops said Thursday.

James Woods was charged with assault Wednesday for repeatedly punching 79-year-old Angel Diaz on Sept. 13 — even as he was down on the ground — leading to his death more than a month later, cops said.

Woods allegedly approached Diaz in front of 46 Hoyt St. in downtown Brooklyn and punched him, knocking him to the pavement, cops said. Woods then hit Diaz multiple times in the face before running away, cops said. 

EMS rushed Diaz to Methodist Hospital, where he was treated for a broken nose, an orbital fracture and bleeding on the brain, police sources said. He was unconscious and unable to speak to cops.

He was later transferred to Bellevue Hospital, where he died on Oct. 29.

The Kings County District Attorney’s Office said additional charges were pending.

 “We expect the charges to be upgraded after consultation with the medical examiner,” said a spokeswoman for the DA’s office.