Last Tuesday, police capped the largest murder investigation in Delaware history by arresting Pennell after watching him round-the-clock for six weeks.
Early the next day, Pennell was charged with DiMauro's death and ordered held without bail at Gander Hill Prison in Wilmington.
Yesterday, the grand jury interviewed police investigators, and looked at forensic evidence and photos of the crime scenes before returning its indictment, said Peter Letang, a state prosecutor.
The state Attorney General's Office was not ready to ask the grand jury to indict Pennell in the death of Margaret Lynn Finner, 27, of Wilmington, or the disappearance of Kathleen Anne Meyer, 26, of Newark, Letang said.
Pennell is scheduled for arraignment Dec. 14 in Superior Court, but he may be arraigned as early as today, said Eugene Maurer Jr., his attorney.
Meanwhile, Pennell "still maintains his innocence" as he waits in a solitary cell at Gander Hill, Maurer said.
Pennell was moved to the cell from the prison infirmary, where he was first jailed last week to protect him from other inmates because of the nature of the charges, Maurer said. Now, a prison guard follows him when he leaves his cell, Maurer said.
On Nov. 29, 1987, exactly one year before Pennell's arrest, a passer-by found Ellis' body in the Old Baltimore Pike Industrial Park, 10 miles southwest of Wilmington.
Construction workers discovered DiMauro's body June 29 at a housing site near Routes 7 and 72, about three miles north of Newark and four miles from where Ellis was found.
Boaters found Gordon's nude body Sept. 20 on rocks in the Chesapeake & Delaware Canal.
Margaret Lynn Finner's decomposed body was found Nov. 12 near the canal. Kathleen Anne Meyer, 26, of Newark, who was last seen Sept. 10, is presumed dead. No one has been charged in their cases.
Police have said that they believe that Finner and Meyer were victims of the same person who killed the other three women, but the grand jury did not review their cases yesterday, Letang said.
"The investigation is still continuing (on) Margaret Lynn Finner, we're still working on it," Letang said. "We were not comfortable presenting that to the grand jury at that time."
As for Meyer, Letang said, "We have no body. If you don't have a body, it's tough to establish she's even deceased."
Pennell probably will not go to trial until next fall, Letang said.