Explaining that they could not meet a 35-day deadline for securing an indictment, District of Columbia prosecutors yesterday dropped charges against Robert Earl (Drop) Lyons, who had been arrested for shooting and wounding a federal prosecutor.

Lyons, a 28-year-old Narthwest resident, will remain incarcerated indefinitely, according to the U.S. Attorney's office here. He is wanted in New York State for a parole violation and is expected to be extradicted there from the D.C. Jail, where he has been held in lieu of $100,000 bond on charges of conspiracy to murder a federal officer.

John Perazich, Lyons' court-appointed fattorney, said yesterday that the dropping of charges "in no meaningful sense alters things." He said he expected Lyond to be indicted within a few weeks, after prosecutors "have had an opportunity to fully explore the case."

Assistant U.S. Attorney Barry Leibowitz was hospitalized for a day, then released, after being shot above the right hip as he walked to work at the U.S. courthouse here in December.

Leibowitz has said that he had a clear view of the gunman, who shot from a car and fled. Leibowitz testified at Lyons' preliminary hearing that he had positively identified him from an array of photographs after his recollection was refreshed at one point through the use of hypnosis.

Lyons was arrested last Jan. 30 and charged with conspiracy to murder a federal officer.

Government attorneys said yesterday that while they felt they had a good case against Lyons, "35 days (from date of arrest) was not enough time to break a relatively complex conspiracy." Prosecutors indicated that they would bring charges against Lyons after gathering more evidence.

Leibowitz was investigating an alleged heroinsmuggling ring when he was shot and prosecutors have said they believed the shooting was tied to that investigation.

Linwood Gray, a 34-year-old Southeast man, was arrested last Jan. 26 and charged with masterminding the alleged ring. Prosecutors since have obtained an extension of the 35-day time limit in Gray's case, and have until next Monday to indict him. He currently is jailed in lieu of bond.