SALEM – A Swampscott man, facing a potential life sentence for robbing Spiro’s Gas Station in Swampscott at gunpoint and stealing about $300 last fall, was held on $20,000 cash bail, after pleading innocent.Joshua Enos, 19, of 34 Hillcrest Circle, appeared for his arraignment Monday afternoon in Salem Superior Court, pleading innocent to a charge of armed robbery before Judge Timothy Q. Feeley.Assistant District Attorney A.J. Camelio and defense lawyer Mark Schmidt jointly recommended the bail. Feeley left the door open for a bail review hearing at another court date.Camelio filed a motion ordering Enos to provide the commonwealth with a DNA sample, which the judge allowed. In asking for the DNA sample, Camelio told Feeley that the sample is important since a mask was found near the crime with possibly the suspect’s DNA profile on it and that the gas station attendant had identified the mask as part of the robber’s attire.On Oct. 5, 2009, at Spiro’s, 620 Humphrey St., a white male with a medium build and blue eyes wearing a black hooded sweatshirt and black mask walked into the station wielding a black handgun. He demanded money as he put the gun in the male attendant’s face.The attendant turned over approximately $300.A black mask found nearby on Pleasant Street in Swampscott was sent to the state crime unit the following day for DNA analysis. The lab said the DNA belonged to Joshua Enos, said Camelio.A warrant was issued for the arrest of Enos, who was in custody at the time for suspected housebreaks in other communities.Enos, who remains held at the Middleton Jail on bail, is scheduled to return to court on Nov. 19 for a pretrial conference.