The criminal known as the Death-Stalker was Phillip Wallace Sterling, the last member of an old, wealthy and prestigious family that had lived in America for centuries. It is not known why Sterling turned to crime.
He conducted his first known criminal activities under the alias of the Exterminator. In this role, Sterling was the costumed mastermind behind a series of crimes committed by the original criminals known as the Unholy Three (Ape-Man, Cat-Man, and Bird-Man.) During a clash with the costumed crime fighter Daredevil, Ape-Man succeeded in exiling Daredevil to the void with his T-ray gun. Daredevil was able to use his powers and skills to escape through a dimension warp, and tracked the Exterminator and the Unholy Three to their lair. After defeating the four, Daredevil intentionally triggered the explosion of the Exterminator's main displacement machine, hoping to end his superhero career by feigning his own death with the explosion. Unbeknownst to him, however, the same explosion irradiated the Exterminator with an extraordinary amount of the radiation, which permanently trapped the villain in the interdimensional realm.
Soon, Sterling learned how to manifest himself in the Earth dimension, although he would invariably be drawn back into his limbo-state. Realizing the potential for crime, he adopted a new code-name of Death-Stalker. He stole a blue print from the criminal science organization AIM and used them to create his "touch of death" gloves. At the same time, he began to steal components necessary to build a T-ray machine that would allow him to return to Earth permanently. However, Sterling was continually thwarted in this endeavor by Daredevil. He also faced a number of other heroes including Nighthawk, Dr, Strange and Iron Man.
Blaming Daredevil for his condition, Sterling learned of Daredevil's secret identity and hired and outfitted a new Unholy Three, sending them to capture Daredevil in his secret identity. The new Ape-Man and Cat-Man succeeded, and Sterling promptly killed them. Revealing his true identity to Daredevil, Sterling demanded a final battle. At the height of battle, however, Sterling, full of rage, miscalculated his attack and re-materialized in this dimension too soon, solidifying while passing through a tombstone. As a result, Sterling was immediately killed.
Seeking to avenge her son's death, Sterling's mother, Elizabeth Dawes Sterling, used her fortune to construct a series of death-traps within her enormous mansion. She had a large number of identical robots, all in the form of a little girl, built to lure Daredevil into the house. However, Mrs. Sterling died before Daredevil was induced into the mansion.
Sterling apears to have used his intra-dimensional powers to return . However he appears to be in a demented and somewhat confused state.
As the Death-Stalker, Sterling ordinarily existed in an interdimensional realm lying close to Earth's dimension. From this dimension he could observe Earth without being seen. He could also temporarily materialize on Earth, either as an intangible "phantom" or as a solid figure. He could materialize on Earth for up to five hours but must rest in his interdimensional realm for at least that much time before returning. Sterling could also "teleport" by moving quickly through his interdimensional realm, then reappearing on Earth an equal distance away. The accident that left him with this ability also radically altered his appearance into a chalk-white skin.
As the Exterminator, Sterling used in own invention, a weapon he called a "time displacer ray," or "T-ray," which could project its victim into a limbo-like interdimensional void. (Sterling initially believed he was banishing victims to another "time continuum.") Overall, Sterling would give the impression that his weapon actually disintegrated his victims, although they would normally return after a specified number of hours.
Sterling also designed a pair of cybernetic death-grip devices which he wore underneath his gloves. He needed to be in solid form and touch his victim to bombard the victim with microwaves, effectively killing him within seconds.