New Orleans sniperasrianNEW ORLEANS (AP) - Police have identified the sniper they killed on a hotel rooftop as ' a young Kansas black whose minister says he “hated white folks.”Supt. Clarence Giarrusso told a news, conference Tuesday that the sniper was Mark J. Essex, 23, of Emporia and added: “There’s some evidence of a conspiracy by other people, but I cannot positively tell you yet.”. Six persons were shot to' death and 17 injured in the sniping incident.Giarrusso also said:— Ballistics prove a .44 magnum carbine found next to Essex’ body was the same wea- , pon that killed a young police cadet and wounded a policeman in New Orleans on New Year’s Eve.— Police “have evidence that would lead to both conclusions” — that Essex was the ‘ only sniper on the roof of the DownTown Howard Johnson’s hotel, and that one or more fellow snipers were with him and escaped. ,' Asked whether his reference to conspiracy meant he had evidence Essex belonged to a militant organization, Giarrusso said: ^“I’m not certain about that yet ... (but) conspiracy in the sense that it may have been two, three or four people; a small number —' you know, it doesn’t take many to form a conspiracy — who were intent to kill people. And . that’s thesum and essence of it.”He said the carbine was the same weapon that cut down cadet Alfred Harrell, 19, as he stepped in front of police headquarters 10 days ago and wounded Patrolman Edwin C. Hosli Sr., 18 minutes later a few blocks away.At the time of the New Year’s Eve shootings, Giarrusso said, “We had some information — reason to believe people were going to hurt someone when'Harrell and Hosli were taken to Charity Hospital.”On the basis of that information, during the sniping he deployed extra officers at the hospital, where following a brief disturbance a man with a shotgun was arrested.In Essex’ hometown of Emporia, the Rev. W. A. Chambers. his family’s minister, said young Essex had developed a militant dislike f6r whites when he came home from the Navy.In Washington, the Navy said Essex was given a general discharge for unsuitability Feb. 10, 1970. A spokesman said this type of discharge -involves “character and behavior disorders” but would not elaborate.Meanwhile, police debated whether there was more than one sniper.Giarrusso gave these reasons to think Essex wasn’t alone:_ — After his death, a helicopter which participated in a police seige on the hotel was firedupon. “You’d have to assume the police hit the plane (if Essex was alone). This is possible, but highly improbable.”— After Essex died, several policemen saw another person on the roof. “There were very, very many shots taken at this person while this person, or this ghost allegedly moved.... I can’t believe that the policemen :.7 were all hallucinating.”— Policemen heard foul language and shouting and talking on the rooftop after Essex was killed.Giarrusso cited these reasons for believing Essex acted alone.— “There has been but one person found.”— “Our men insisl the area was adequately sealed off.”However, under close questioning, Giarrusso conceded that “there was a time span prior to our receipt of the plans of the building that an un-obvious exit from the roof would have enabled other persons, if there were any, to leave the roof and go to another floor.”He1 said he didn’t know the length of the “time span,” but that it was at the very beginning of the siege. Under more questioning, Giarrusso identified the “unobvious exit” as the elevator shaft.'Newsmen .inside the hotel said police didn’t begin guarding the bottom of the elevator shafts until after sunrise Monday — or nearly 24 hours after the shooting started.