Haggerty said FBI technicians would test the blood's genetic DNA pattern for a possible match to two murder victims: Michele A. Gordon, 22, of New Castle County, and Margaret Lynn Finner, 27, of Wilmington.
The case of Gordon, who died in September 1988, ended in a mistrial last week.
Finner's skeletal remains, found Nov. 12, 1988, did not yield enough evidence for prosecutors to present to a grand jury last December. She was last seen getting into a blue van similar to Pennell's at 11:30 p.m. Aug. 22, 1988, near New Castle, Del.
Police also suspect Pennell in the disappearance of Kathleen Anne Meyer, 26, of Brookmont Farms, near Newark, Del. She was last seen Sept. 10, 1988, and is presumed dead. Her body has not been recovered.
Pennell, 32, of Glasgow, Del., was convicted last Thursday of murdering two Newark, Del., women - Shirley A. Ellis, 23, in November 1987 and Catherine A. DiMauro, 32, in June 1988.
However, jurors deadlocked on the Gordon case, and Superior Court Judge Richard S. Gebelein declared a mistrial.
Prosecutors will decide within two months whether to retry Pennell for Gordon's death, said Delaware Attorney General Charles M. Oberly 3d.
Meanwhile, state and New Castle County police are re-examining evidence in the deaths of Gordon, Finner and Meyer, Haggerty said.
"We've made a commitment to see this thing through," county police chief Col. Thomas P. Gordon said. "I'm sure that (the women's families) would like to see (Pennell) prosecuted for the other deaths."
All five women disappeared along the highway corridor formed by U.S. Routes 13 and 40 near New Castle, which is frequented by prostitutes.
Witnesses testified that Ellis, DiMauro and Gordon had worked as prostitutes along Routes 13 and 40, and prostitution activity slowed in the area last year when the bodies were found, police said.
After Pennell's conviction, a bouquet of flowers was sent Monday to Deputy Attorney General Kathleen Jennings.
The card read, "Congratulations, Ms. Jennings and staff (Men do not usually get flowers). Grateful appreciation for preserving the dignity of all human life . . . and justice was done. Women of 13/40."
Gebelein sentenced Pennell to two life terms without parole Tuesday after jurors deadlocked on whether he should be executed by lethal injection.
Pennell was placed in a cell by himself in Gander Hill Prison in Wilmington, where guards check on him every 15 minutes, Warden Elizabeth Neal said yesterday.
"He's been sequestered from the general population, along with other protective-custody inmates . . . because of his notoriety and the nature of the offenses with which he is charged," Neal said. Pennell is allowed out of his cell for about an hour a day for showering, exercise and personal chores, she said.