Mark Anthony Cassell, 36, is scheduled to be arraigned this afternoon on murder charges in connection with the Jan. 28 attack on 77-year-old San Francisco Chronicle vendor Dallas Ayers at 1 Post St.
After the attack, Ayers was taken to a hospital, where he died on Feb. 21.
Cassell was arrested on March 13 but prosecutors initially declined to pursue murder charges against him.
However, after additional evidence was presented to them, they made the decision on Friday to charge him with murder, district attorney's office spokesman Alex Bastian said.
Police have alleged that Cassell approached Ayers, wrapped his arms around his waist, picked him up and dropped him to the ground.
Cassell was arrested after officers from the department's Tenderloin station recognized him from a department-wide bulletin.
He had a bench warrant out for his arrest on methamphetamine possession and petty theft charges, and remained in jail on $10,000 bail while prosecutors mulled whether to file the murder charges.