Officers responded to a 911 call of an unconscious female bleeding inside 325 Roebling Street around 8 p.m.
Witnesses said the man ran from the apartment toward the roof.
The officers followed the man and watched him jump, police said.
Efriam Gabourel, 26, was pronounced dead at the scene.
The woman, who also lived in the building, has been identified as 29-year-old Liliana Belfor.
The investigation is ongoing.